CMake: Detect attempts to BULD_SHARED_LIBS on non-Linux and fail.
Merge pull request #711 from klickverbot/shared-error

CMake: Detect attempts to BULD_SHARED_LIBS on non-Linux and fail.
CMake: Remove outdated TODO.

See dc() for the workarounds in question.
CMake: Adjust internal target names when LIB_SUFFIX is specified.

GitHub: Fixes #712.