rusticl: allow devices to be enabled by default

Reviewed-by: David Heidelberg <david@ixit.cz>
Acked-by: Eric Engestrom <eric@igalia.com>
Reviewed-by: Alyssa Rosenzweig <alyssa@rosenzweig.io>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/31202>

meson_options.txt

@@ -160,6 +160,14 @@ option(
   description : 'build gallium "rusticl" OpenCL frontend.',
 )
 
+option(
+  'gallium-rusticl-enable-drivers',
+  type : 'array',
+  value : ['auto'],
+  description : 'List of gallium drivers for which rusticl will be enabled ' +
+                'by default',
+)
+
 option(
   'gallium-wgl-dll-name',
   type : 'string',