Remove {cdefs,types}-compat.h from openlibm.h
Revert "Install everything in the `include/` directory into `$(prefix)/include/openlibm`."

This reverts commit eb2f4d4b44e6ffaede3057d2cb6c6bae77de863f.
Merge noinc branch
Added pkg-config support
Merge pull request #58 from talex5/pkg-config

Add pkg-config support