egl/x11: don't abort when creating a DRI2 drawable fails

egl/x11: don't abort when creating a DRI2 drawable fails

When calling either eglCreateWindowSurface or eglCreatePixmapSurface it
was possible for an application to be aborted as a result of it failing
to create a DRI2 drawable on the server. This could happen due to an
application passing in an invalid native drawable handle, for example.

v2: Handle the case where an error has been set on the connection

Cc: <mesa-stable@lists.freedesktop.org>
Signed-off-by: Frank Binns <frank.binns@imgtec.com>
Reviewed-by: Emil Velikov <emil.l.velikov@gmail.com>