dri: add _glthread_GetID to dri_test.c dummy glapi

src/mesa/drivers/dri/common/dri_test.c

@@ -71,6 +71,12 @@ _glapi_get_dispatch_table_size(void)
 	return 0;
 }
 
+PUBLIC unsigned long
+_glthread_GetID(void)
+{
+   return 0;
+}
+
 int main(int argc, char** argv)
 {
    void* p = __driDriverExtensions;