The previously-specified paths were only correct for a static library
build.
I therefore fenced off that code to be specific to static library
builds.
For shared library builds, I added a generator-expression-based
alternative.
Annoyingly, this won't work with static library builds, so we don't get
the concise, reliable version in all circumstances.
I've avoided modifying any of the paths anything ends up at to avoid
breaking changes.
Resolves https://github.com/assimp/assimp/issues/4269
e50233b2c1