Fix missing libraries.
Squashed 'CMakeModules/' changes from e83ac80..ebfa49d

ebfa49d Merge pull request #1 from arpg/private_linkage
40245bc Makes def_library link privately.
2979d55 Fix install when version string is empty.

git-subtree-dir: CMakeModules
git-subtree-split: ebfa49d8c26ef31a783425596febca3f457820ec
Merge commit '89994e029dd71e11c542c07e57f0f786f0f38db7' into private_linkage
Merge pull request #11 from arpg/private_linkage

Private linkage in CMake.