st/mesa: add extern "C" to st_context.h

Reviewed-by: Anuj Phogat <anuj.phogat@gmail.com>
Reviewed-by: Jose Fonseca <jfonseca@vmware.com>

src/mesa/state_tracker/st_context.h

@@ -33,6 +33,12 @@
 #include "state_tracker/st_api.h"
 #include "main/fbobject.h"
 
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+
 struct bitmap_cache;
 struct dd_function_table;
 struct draw_context;
@@ -278,4 +284,8 @@ extern void
 st_destroy_context(struct st_context *st);
 
 
+#ifdef __cplusplus
+}
+#endif
+
 #endif