The Python.h header varies in location by distribution, so instead use
pkg-config to ensure the python3 devel package is installed. Tested with
Ubuntu 12.04 and Fedora 17. Fixes --enable-python on Fedora 17.
Signed-off-by: Dwight Engen <dwight.engen@oracle.com>
Acked-by: Stéphane Graber <stgraber@ubuntu.com>