[Patch #641685] setup.py contained code for finding libraries, instead

of using the CCompiler.find_library_file() provided by the Distutils.
   This patch fixes it to use the Distutils method at the cost of some
   additional glue.

(The duplication resulted in the SSL module not being automatically
built on Macs; the Distutils knew that shared libraries on OS X have a
.dylib extension, but the setup.py code didn't.)