glx: Fix error return code in GLXGetDrawableAttributes

This should only ever throw GLXBadDrawable, says the protocol spec.
4 jobs for glx-gda-error-fix in 7 minutes and 21 seconds (queued for 1 second)
Status Job ID Name Coverage
  Docker Image
passed #9125944
debian-buster

00:00:13

 
  Build And Test
passed #9125945
autotools

00:07:07

passed #9125946
meson

00:03:36

passed #9125947
meson-noglamor

00:02:55