mesa: Fix Windows GDI winsys build.
diff --git a/src/mesa/SConscript b/src/mesa/SConscript
index af83db0..d2de189 100644
--- a/src/mesa/SConscript
+++ b/src/mesa/SConscript
@@ -231,6 +231,7 @@
 	glapi_sources = [
 		'main/dispatch.c',
 		'glapi/glapi.c',
+		'glapi/glapi_getproc.c',
 		'glapi/glthread.c',
 	]