gl-renderer: fix EGL initialization steps

Some DRI drivers, including VMware vmwgfx, do not support
calling eglQueryString() with a EGL_NO_DISPLAY parameter.
Just as we do in gl_renderer_supports(), which returns 0
but does not fail in this case, do not fail in
gl_renderer_setup_egl_extensions().

Signed-off-by: Manuel Bachmann <manuel.bachmann@open.eurogiciel.org>
[Pekka: split the patch]
Signed-off-by: Pekka Paalanen <pekka.paalanen@collabora.co.uk>
Reviewed-by: Daniel Stone <daniels@collabora.com>

src/gl-renderer.c

@@ -2136,7 +2136,7 @@ gl_renderer_setup_egl_extensions(struct weston_compositor *ec)
 		(const char *) eglQueryString(EGL_NO_DISPLAY, EGL_EXTENSIONS);
 	if (!extensions) {
 		weston_log("Retrieving EGL client extension string failed.\n");
-		return -1;
+		return 0;
 	}
 
 	if (strstr(extensions, "EGL_EXT_platform_base"))