Don't assume c_int64 is available when searching for ptrdiff_t.  Resolves issue #2.
Don't assume c_int64 is available when searching for ptrdiff_t.  Resolves
issue #2.

Austin503/pyglet,mpasternak/pyglet-fix-issue-518-522,Alwnikrotikz/pyglet,mpasternak/michaldtz-fixes-518-522,qbektrix/pyglet,google-code-export/pyglet,shaileshgoogler/pyglet,mpasternak/michaldtz-fix-552,google-code-export/pyglet,Alwnikrotikz/pyglet,google-code-export/pyglet,shaileshgoogler/pyglet,odyaka341/pyglet,kmonsoor/pyglet,odyaka341/pyglet,gdkar/pyglet,Austin503/pyglet,Alwnikrotikz/pyglet,mpasternak/pyglet-fix-issue-518-522,shaileshgoogler/pyglet,odyaka341/pyglet,shaileshgoogler/pyglet,Austin503/pyglet,qbektrix/pyglet,cledio66/pyglet,mpasternak/michaldtz-fixes-518-522,mpasternak/pyglet-fix-issue-518-522,gdkar/pyglet,mpasternak/pyglet-fix-issue-552,arifgursel/pyglet,Austin503/pyglet,kmonsoor/pyglet,Austin503/pyglet,google-code-export/pyglet,xshotD/pyglet,mpasternak/pyglet-fix-issue-552,qbektrix/pyglet,kmonsoor/pyglet,gdkar/pyglet,odyaka341/pyglet,kmonsoor/pyglet,xshotD/pyglet,qbektrix/pyglet,gdkar/pyglet,kmonsoor/pyglet,cledio66/pyglet,mpasternak/pyglet-fix-issue-552,mpasternak/pyglet-fix-issue-518-522,google-code-export/pyglet,odyaka341/pyglet,cledio66/pyglet,qbektrix/pyglet,xshotD/pyglet,mpasternak/michaldtz-fix-552,mpasternak/michaldtz-fix-552,Alwnikrotikz/pyglet,mpasternak/pyglet-fix-issue-552,arifgursel/pyglet,gdkar/pyglet,xshotD/pyglet,arifgursel/pyglet,arifgursel/pyglet,cledio66/pyglet,xshotD/pyglet,cledio66/pyglet,mpasternak/michaldtz-fix-552,shaileshgoogler/pyglet,mpasternak/michaldtz-fixes-518-522,mpasternak/michaldtz-fixes-518-522,Alwnikrotikz/pyglet,arifgursel/pyglet