COMP: Disable 'GitPython' and 'PyGithub' waiting build error are fixed.

This is a temporary solution waiting I finish to generalize the system
used to configure/make/install NUMPY. When done, a similar mechanism
will be used to build python modules requiring a build environment / compiler.

git-svn-id: http://svn.slicer.org/Slicer4/trunk@23065 3bd1e089-480b-0410-8dfb-8563597acbee