Cherry-pick https://github.com/adobe/XMP-Toolkit-SDK/pull/57

Original commit messsage:
==========
Author: Fabrice Fontaine <fontaine.fabrice@gmail.com>

XMPFiles/source/XMPFiles_Impl.cpp: fix arm build with gcc 10

Fix the following build failure with exempi on arm with gcc 10 raised
since version 2.6.0 and
0872e35a
https://github.com/adobe/XMP-Toolkit-SDK/commit/0872e35a30457d2ecf746a1bebdb7d94636d0e2f:

/home/giuliobenetti/autobuild/run/instance-3/output-1/host/lib/gcc/arm-buildroot-linux-uclibcgnueabi/10.3.0/../../../../arm-buildroot-linux-uclibcgnueabi/bin/ld: ../../XMPFiles/source/.libs/libXMPFiles.a(XMPFiles_Impl.o):(.rodata+0x5c): multiple definition of `typeinfo name for TXMPMeta<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > >'; XMPFilesCoverage.o:(.rodata+0x0): first defined here

More information can be found on a similar issue...

#30

Allow the user to disable samples

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>

Expat version upgrade to 2.4.7

Daniel Kolesa authored Apr 03, 2022 and Hubert Figuiere committed Apr 09, 2022

This would, at least on some setups, result in actual API symbols
missing from the library, because the symfile hasn't been changed
for over a decade.

Additionally, it should not be needed anymore as the project
appears to use `-fvisibility=hidden` and actually tag the public
API symbols appropriately.

This fixes tests build with LTO (as long as static libs are not
disabled) besides other issues.

Compiler upgrade for win, mac and iOS

- See !4

- This allow building with -Werror=class-memaccess

- XmpDate and BoxInfo have constructors

- Bump requirement to boost 1.60

Upgrade XMP-SDK to v2021.10

Fixing CTECHXMP-4170583, CTECHXMP-4170596, CTECHXMP-4170597, CTECHXMP-4170598 ,CTECHXMP-4170599, CTECHXMP-4170632 and CTECHXMP-4170633

- Added missing files to build