meson: allow building all glx without any drivers

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=111016
Fixes: a47c525f3281a2753180e076c7e9b7772aff8f06
       ("meson: build glx")
Acked-by: Emil Velikov <emil.velikov@collabora.com>
Reviewed-by: Eric Anholt <eric@anholt.net>
diff --git a/meson.build b/meson.build
index 13b561f..804b921 100644
--- a/meson.build
+++ b/meson.build
@@ -315,7 +315,7 @@
    endif
 endif
 
-if not (with_dri or with_gallium or with_glx == 'xlib' or with_glx == 'gallium-xlib')
+if not (with_dri or with_gallium or with_glx != 'disabled')
   with_gles1 = false
   with_gles2 = false
   with_opengl = false
@@ -382,9 +382,7 @@
       error('xlib conflicts with any dri driver')
     endif
   elif with_glx == 'dri'
-    if not with_dri
-      error('dri based GLX requires at least one DRI driver')
-    elif not with_shared_glapi
+    if not with_shared_glapi
       error('dri based GLX requires shared-glapi')
     endif
   endif