Clear the ccache in the travis C builds before running the tests since it seems to be corrupted.
Clear the ccache in the travis C builds before running the tests since it seems to be corrupted.

da-woods/cython,scoder/cython,cython/cython,da-woods/cython,scoder/cython,da-woods/cython,cython/cython,scoder/cython,da-woods/cython,cython/cython,scoder/cython,cython/cython