The .pc files in src/ are intended for use with the ./run script,
to ease building bindings against an uninstalled libvirt build.
The pointer to the API XML files is incorrect though, it needs to
point into the build tree.

This fixes use of the run script for building libvirt-python, ex:

  /path/to/libvirt.git/run ./setup.py build
Reviewed-by: NDaniel P. Berrangé <berrange@redhat.com>
Signed-off-by: NCole Robinson <crobinso@redhat.com>