meson: build gallium nine state_tracker

v2: - set d3d_drivers_path instead of dri_drivers_path
    - Fix nine guard to check for all relavent gallium drivers
    - Link with libswdri and libswkmsdri when necessary
    - Fix pkg-config generation
    - Add missing comma

Signed-off-by: Dylan Baker <dylanx.c.baker@intel.com>
Reviewed-by: Eric Engestrom <eric.engestrom@imgtec.com>

meson_options.txt

@@ -114,6 +114,18 @@ option(
   choices : ['auto', 'true', 'false'],
   description : 'enable gallium xa state tracker.',
 )
+option(
+  'gallium-nine',
+  type : 'boolean',
+  value : false,
+  description : 'build gallium "nine" Direct3D 9.x state tracker.',
+)
+option(
+  'd3d-drivers-path',
+  type : 'string',
+  value : '',
+  description : 'Location of D3D drivers. Default: $libdir/d3d',
+)
 option(
   'vulkan-drivers',
   type : 'string',