2.5.1: test suite build fails (because of LTO)

make[3]: 'testparse' is up to date.
/bin/sh ../../libtool  --tag=CXX   --mode=link g++  -O2 -g -pipe -Wall -Werror=format-security -Wp,-D_FORTIFY_SOURCE=2 -Wp,-D_GLIBCXX_ASSERTIONS -fstack-protector-strong -grecord-gcc-switches -specs=/usr/lib/rpm/redhat/redhat-hardened-cc1 -specs=/usr/lib/rpm/redhat/redhat-annobin-cc1 -m64 -mtune=generic -fasynchronous-unwind-tables -fstack-clash-protection -fcf-protection  -fvisibility=hidden -Wchar-subscripts -Wcast-align -Wextra -Wformat -Wformat-security -Wlogical-not-parentheses -Wmisleading-indentation -Wmissing-noreturn -Woverloaded-virtual -Wpointer-arith -Wshadow -Wsign-compare -Wno-suggest-attribute=noreturn -Wunreachable-code -Wunused -Wwrite-strings -static  -Wl,-z,relro -Wl,--as-needed  -Wl,-z,now -specs=/usr/lib/rpm/redhat/redhat-hardened-ld  -o testiterator test-iterator.o utils.o ../libexempi.la -lboost_unit_test_framework 
libtool: link: g++ -O2 -g -pipe -Wall -Werror=format-security -Wp,-D_FORTIFY_SOURCE=2 -Wp,-D_GLIBCXX_ASSERTIONS -fstack-protector-strong -grecord-gcc-switches -specs=/usr/lib/rpm/redhat/redhat-hardened-cc1 -specs=/usr/lib/rpm/redhat/redhat-annobin-cc1 -m64 -mtune=generic -fasynchronous-unwind-tables -fstack-clash-protection -fcf-protection -fvisibility=hidden -Wchar-subscripts -Wcast-align -Wextra -Wformat -Wformat-security -Wlogical-not-parentheses -Wmisleading-indentation -Wmissing-noreturn -Woverloaded-virtual -Wpointer-arith -Wshadow -Wsign-compare -Wno-suggest-attribute=noreturn -Wunreachable-code -Wunused -Wwrite-strings -Wl,-z -Wl,relro -Wl,--as-needed -Wl,-z -Wl,now -specs=/usr/lib/rpm/redhat/redhat-hardened-ld -o testiterator test-iterator.o utils.o  ../.libs/libexempi.so -lexpat -lz -ldl -lrt -lboost_unit_test_framework -Wl,-rpath -Wl,/home/tkloczko/rpmbuild/BUILD/exempi-2.5.1/exempi/.libs
make[3]: 'testinit' is up to date.
make[3]: 'testfdo18635' is up to date.
make[3]: 'testfdo83313' is up to date.
make[3]: 'testcpp' is up to date.
make[3]: 'testwebp' is up to date.
/bin/sh ../../libtool  --tag=CXX   --mode=link g++  -O2 -g -pipe -Wall -Werror=format-security -Wp,-D_FORTIFY_SOURCE=2 -Wp,-D_GLIBCXX_ASSERTIONS -fstack-protector-strong -grecord-gcc-switches -specs=/usr/lib/rpm/redhat/redhat-hardened-cc1 -specs=/usr/lib/rpm/redhat/redhat-annobin-cc1 -m64 -mtune=generic -fasynchronous-unwind-tables -fstack-clash-protection -fcf-protection  -fvisibility=hidden -Wchar-subscripts -Wcast-align -Wextra -Wformat -Wformat-security -Wlogical-not-parentheses -Wmisleading-indentation -Wmissing-noreturn -Woverloaded-virtual -Wpointer-arith -Wshadow -Wsign-compare -Wno-suggest-attribute=noreturn -Wunreachable-code -Wunused -Wwrite-strings -static  -Wl,-z,relro -Wl,--as-needed  -Wl,-z,now -specs=/usr/lib/rpm/redhat/redhat-hardened-ld  -o testadobesdk test-adobesdk.o ../libexempi.la -lboost_unit_test_framework 
libtool: link: g++ -O2 -g -pipe -Wall -Werror=format-security -Wp,-D_FORTIFY_SOURCE=2 -Wp,-D_GLIBCXX_ASSERTIONS -fstack-protector-strong -grecord-gcc-switches -specs=/usr/lib/rpm/redhat/redhat-hardened-cc1 -specs=/usr/lib/rpm/redhat/redhat-annobin-cc1 -m64 -mtune=generic -fasynchronous-unwind-tables -fstack-clash-protection -fcf-protection -fvisibility=hidden -Wchar-subscripts -Wcast-align -Wextra -Wformat -Wformat-security -Wlogical-not-parentheses -Wmisleading-indentation -Wmissing-noreturn -Woverloaded-virtual -Wpointer-arith -Wshadow -Wsign-compare -Wno-suggest-attribute=noreturn -Wunreachable-code -Wunused -Wwrite-strings -Wl,-z -Wl,relro -Wl,--as-needed -Wl,-z -Wl,now -specs=/usr/lib/rpm/redhat/redhat-hardened-ld -o testadobesdk test-adobesdk.o  ../.libs/libexempi.so -lexpat -lz -ldl -lrt -lboost_unit_test_framework -Wl,-rpath -Wl,/home/tkloczko/rpmbuild/BUILD/exempi-2.5.1/exempi/.libs
/usr/bin/ld: test-adobesdk.o: in function `test_adobesdk::test_convertToInt64::test_method()':
/home/tkloczko/rpmbuild/BUILD/exempi-2.5.1/exempi/tests/test-adobesdk.cpp:68: undefined reference to `XMPUtils::ConvertToInt64(char const*)'
/usr/bin/ld: /home/tkloczko/rpmbuild/BUILD/exempi-2.5.1/exempi/tests/test-adobesdk.cpp:71: undefined reference to `XMPUtils::ConvertToInt64(char const*)'
/usr/bin/ld: /home/tkloczko/rpmbuild/BUILD/exempi-2.5.1/exempi/tests/test-adobesdk.cpp:74: undefined reference to `XMPUtils::ConvertToInt64(char const*)'
/usr/bin/ld: test-adobesdk.o: in function `test_adobesdk::test_composeArray::test_method()':
/home/tkloczko/rpmbuild/BUILD/exempi-2.5.1/exempi/tests/test-adobesdk.cpp:32: undefined reference to `XMPUtils::ComposeArrayItemPath(char const*, char const*, int, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >*)'
/usr/bin/ld: /home/tkloczko/rpmbuild/BUILD/exempi-2.5.1/exempi/tests/test-adobesdk.cpp:34: undefined reference to `XMPUtils::ComposeArrayItemPath(char const*, char const*, int, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >*)'
/usr/bin/ld: /home/tkloczko/rpmbuild/BUILD/exempi-2.5.1/exempi/tests/test-adobesdk.cpp:36: undefined reference to `XMPUtils::ComposeArrayItemPath(char const*, char const*, int, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >*)'
/usr/bin/ld: /home/tkloczko/rpmbuild/BUILD/exempi-2.5.1/exempi/tests/test-adobesdk.cpp:39: undefined reference to `XMPUtils::ComposeArrayItemPath(char const*, char const*, int, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >*)'
/usr/bin/ld: /home/tkloczko/rpmbuild/BUILD/exempi-2.5.1/exempi/tests/test-adobesdk.cpp:43: undefined reference to `XMPUtils::ComposeArrayItemPath(char const*, char const*, int, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >*)'
/usr/bin/ld: test-adobesdk.o: in function `test_adobesdk::test_composeStructFieldPath::test_method()':
/home/tkloczko/rpmbuild/BUILD/exempi-2.5.1/exempi/tests/test-adobesdk.cpp:52: undefined reference to `XMPUtils::ComposeStructFieldPath(char const*, char const*, char const*, char const*, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >*)'
/usr/bin/ld: /home/tkloczko/rpmbuild/BUILD/exempi-2.5.1/exempi/tests/test-adobesdk.cpp:54: undefined reference to `XMPUtils::ComposeStructFieldPath(char const*, char const*, char const*, char const*, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >*)'
/usr/bin/ld: /home/tkloczko/rpmbuild/BUILD/exempi-2.5.1/exempi/tests/test-adobesdk.cpp:56: undefined reference to `XMPUtils::ComposeStructFieldPath(char const*, char const*, char const*, char const*, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >*)'
/usr/bin/ld: /home/tkloczko/rpmbuild/BUILD/exempi-2.5.1/exempi/tests/test-adobesdk.cpp:58: undefined reference to `XMPUtils::ComposeStructFieldPath(char const*, char const*, char const*, char const*, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >*)'
/usr/bin/ld: /home/tkloczko/rpmbuild/BUILD/exempi-2.5.1/exempi/tests/test-adobesdk.cpp:61: undefined reference to `XMPUtils::ComposeStructFieldPath(char const*, char const*, char const*, char const*, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >*)'
/usr/bin/ld: test-adobesdk.o: in function `Fixture::~Fixture()':
/home/tkloczko/rpmbuild/BUILD/exempi-2.5.1/exempi/tests/test-adobesdk.cpp:20: undefined reference to `XMPMeta::Terminate()'
/usr/bin/ld: test-adobesdk.o: in function `Fixture::Fixture()':
/home/tkloczko/rpmbuild/BUILD/exempi-2.5.1/exempi/tests/test-adobesdk.cpp:17: undefined reference to `XMPMeta::Initialize()'
collect2: error: ld returned 1 exit status
make[3]: *** [Makefile:789: testadobesdk] Error 1
make[3]: Leaving directory '/home/tkloczko/rpmbuild/BUILD/exempi-2.5.1/exempi/tests'
make[2]: *** [Makefile:1241: check-am] Error 2
make[2]: Leaving directory '/home/tkloczko/rpmbuild/BUILD/exempi-2.5.1/exempi/tests'
make[1]: *** [Makefile:754: check-recursive] Error 1
make[1]: Leaving directory '/home/tkloczko/rpmbuild/BUILD/exempi-2.5.1/exempi'