webkit: fix compilation without X11

Fixes:
 http://autobuild.buildroot.net/results/86534588d192fe1515ce520c109e884864871d94/


and others.

Webkit includes X11 headers even when configuerd for DirecfFB, because
the test within GNUmakefile.in does not work properly. Autoreconfigure
fails because of incompatibility with buildroot's autotools version.

For now a patch for GNUmakefile.in fixes this problem.

Since webkit release is quite old it doesn't seem to be worth doing more,
on the long run we should bump the version.

Signed-off-by: Stephan Hoffmann <sho@relinux.de>
Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>