XCDF Python bindings won't run on OS X with Python >2.7.8

[sybenzvi]

When building XCDF against a homebrewed Python (2.7.9) in Yosemite 10.10.3, the program compiles perfectly but the Python bindings crash when calling "import xcdf" in a Python session.

It seems to be a CMake issue in which FIND_PACKAGE(PythonLibs) grabs the system Python rather than the homebrewed version. Unfortunately the same error also occurs if building against the same version of Python installed with ape.

The CMake issue with FIND_PACKAGE(PythonLibs) is a known problem (Homebrew/legacy-homebrew#25118). The issue with ape is new. There doesn't appear to be an issue with the XCDF code but the build system needs to be fixed.

[sybenzvi]

I think this is fixed. I just force CMake to look in PYTHONHOME first, so the user has to define PYTHONHOME to point to /usr/local if Python is installed by homebrew. It's a hack but there doesn't seem to be a better solution at the moment.