glx: set the loader_logger early and for everyone

glx: set the loader_logger early and for everyone

Currently we set the logger only for DRI3. Even though it's used nearly
everywhere. For platforms where we don't the function is effectively a
no-op.

With this in place, LIBGL_DEBUG=verbose works across the board.

Fixes: d971a4230d5 ("loader: Factor out the common driver opening logic from each loader.")
Cc: Eric Anholt <eric@anholt.net>
Signed-off-by: Emil Velikov <emil.velikov@collabora.com>
Reviewed-by: Adam Jackson <ajax@redhat.com>
Reviewed-by: Eric Engestrom <eric@engestrom.ch>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/4084>