native_gfx: x11: add missing inclusion of <X11/Xutil.h>
native_gfx: x11: add missing inclusion of <X11/Xutil.h>

This fixes build failures, in some situations. This was not detected in
most Linux distributions, as Xutil.h was indirectly included in
<EGL/eglplatform.h>.

Since we need it for XSizeHints type, for example, we need to include it
for correctness.

Signed-off-by: Julien Olivain <e017b3aecfdd2dc1bdcf241eeb088a15ff1e3ada@free.fr>

jolivain/glslsandbox-player,jolivain/glslsandbox-player,jolivain/glslsandbox-player,jolivain/glslsandbox-player