cogl/cogl.c: Do not crash if GLX cannot be initialized
Problems initializing OpenGL cause the following crash:
Program received signal SIGSEGV, Segmentation fault.
_cogl_check_extension (name=0x8239b9e00 "GLX_EXT_texture_from_pixmap",
ext=0x0)
at cogl.c:75
75 while (*ext)
Fixes: https://bugzilla.gnome.org/show_bug.cgi?id=793735
Signed-off-by: Marcin Cieślak saper@saper.info
Edited by Marcin Cieślak