cmake: Add an interpreter-based hint for the Python library search.
cmake: Add an interpreter-based hint for the Python library search.

Uses the `LIBDIR` config variable in Python to get the path for the
interpreter's dynamic library. This is the first path used to search for
the python dynamic library. However, this will likely be the only path
required.

funkey/vigra,dstoe/vigra,funkey/vigra,funkey/vigra,dagophil/vigra,funkey/vigra,funkey/vigra,dagophil/vigra,dagophil/vigra,dagophil/vigra,funkey/vigra,dstoe/vigra,funkey/vigra,dagophil/vigra,dstoe/vigra,dstoe/vigra,dstoe/vigra,dagophil/vigra,dstoe/vigra,dagophil/vigra,dstoe/vigra