CMake parity with Makefile

[Zopolis4]

The CMake build option does not seem to have support for installing the built library, nor does it produce both static and shared libraries. Additionally, it also does not create an openlibm.pc file, nor does it seem to have support for installing headers.

[ViliusSutkus89]

Hello @Zopolis4 , everything you've mentioned except openlibm.pc would be handled by #302

[Zopolis4]

Thanks! It's certainly a step in the right direction, but I do need the openlibm.pc file to be able to switch buildsystems. I can't re-open the issue myself, though.