mesa: refactor: move scissor functions into new scissor.c file
(cherry picked from commit 4be7296bfcba22a849f949d105ea385e6964cc25)
diff --git a/src/mesa/main/context.c b/src/mesa/main/context.c
index ef1c417..a400550 100644
--- a/src/mesa/main/context.c
+++ b/src/mesa/main/context.c
@@ -111,6 +111,7 @@
 #include "polygon.h"
 #include "queryobj.h"
 #include "rastpos.h"
+#include "scissor.h"
 #include "simple_list.h"
 #include "state.h"
 #include "stencil.h"