build: Fix a warning for Autoconf
Remove this warning:
server/Makefile.am:5: warning: SUBDIRS was already defined in condition TRUE, which includes condition ENABLE_TESTS ... server/Makefile.am:2: ... 'SUBDIRS' previously defined here
This was caused by the recent commit 38c7964d ("build: Make building the test binaries optional under Autoconf")
This problems was also causing some issues as "noinst_PROGRAMS" target were not compiled as expected.
Signed-off-by: Frediano Ziglio fziglio@redhat.com