meson: Add support for gallium extra hud

Signed-off-by: Dylan Baker <dylanx.c.baker@intel.com>
Reviewed-by: Eric Engestrom <eric.engestrom@imgtec.com>
diff --git a/meson.build b/meson.build
index aa923cd..2115871 100644
--- a/meson.build
+++ b/meson.build
@@ -922,6 +922,10 @@
   endif
 endif
 
+if get_option('gallium-extra-hud')
+  pre_args += '-DHAVE_GALLIUM_EXTRA_HUD=1'
+endif
+
 # TODO: nine
 
 # TODO: clover