Seems CMake will rearrange and copy libraries which are passed to the linker
when some of the libraries is listed twice (for example, -lz from png libraries
and -l for blender itself). This was causing libopenimageio to be added somewhere
at the end of linking flags without -ldl followed after which was causing linking
issues.
Basically title says it all.
The goal is to make platform maintenance easier, so you don't have
to constantly scroll back and forth looking for if() branches to
check which exact platform you're currently working on.
Ideally we also would move option defaults to a platform files,
but that i'm not sure how to implement in a nice way yet.
Reviewers: mont29
Reviewed By: mont29
Differential Revision: https://developer.blender.org/D2148
