glx: Fix error return code in GLXGetDrawableAttributes

This should only ever throw GLXBadDrawable, says the protocol spec.
5 jobs for glx-gda-error-fix in 19 minutes and 36 seconds (queued for 3 seconds)
Status Job ID Name Coverage
  Docker Image
passed #10255355
debian-buster

00:13:21

 
  Build And Test
passed #10255356
autotools

00:06:14

passed #10255357
meson

00:03:22

passed #10255358
meson-noglamor

00:02:33

passed #10255359
mingw-cross-build

00:01:12