FreeImage fails to build on Arm

[bedroge]

See EESSI/software-layer#736 (comment) and the comments below that one, and https://sourceforge.net/p/freeimage/bugs/325/.

TLDR: FreeImage ships and builds the sources of some dependencies, e.g. zlib, libpng, libopenjpeg, etc. The libpng sources don't include the Neon code, though, causing errors when you try to link the shared library.

Using -DPNG_ARM_NEON_OPT=0 works around the issue, but it completely disables Neon. It would be better to replace all these shipped dependencies by EB-provided dependencies. Gentoo does the latter by using this "unbundling patch" in combination with a bunch of pre-build commands.