Make skia almost compile again with clang.

src/core/SkRTree.cpp

Index: src/core/SkRTree.cpp
diff --git a/src/core/SkRTree.cpp b/src/core/SkRTree.cpp
index 95e4336ac779d4f438a49201d26276294f0ccccf..b6f8e95deac7953ec819323749db0085327cc538 100644
--- a/src/core/SkRTree.cpp
+++ b/src/core/SkRTree.cpp
@@ -1,4 +1,3 @@
-
 /*
  * Copyright 2012 Google Inc.
  *
@@ -12,8 +11,6 @@
 static inline uint32_t get_area(const SkIRect& rect);
 static inline uint32_t get_overlap(const SkIRect& rect1, const SkIRect& rect2);
 static inline uint32_t get_margin(const SkIRect& rect);
-static inline uint32_t get_overlap_increase(const SkIRect& rect1, const SkIRect& rect2,
-                                            SkIRect expandBy);
 static inline uint32_t get_area_increase(const SkIRect& rect1, SkIRect rect2);
 static inline void join_no_empty_check(const SkIRect& joinWith, SkIRect* out);
 
@@ -471,12 +468,6 @@ static inline uint32_t get_margin(const SkIRect& rect) {
     return 2 * (rect.width() + rect.height());
 }
 
-static inline uint32_t get_overlap_increase(const SkIRect& rect1, const SkIRect& rect2,
-                                          SkIRect expandBy) {
-    join_no_empty_check(rect1, &expandBy);
-    return get_overlap(expandBy, rect2) - get_overlap(rect1, rect2);
-}
-
 static inline uint32_t get_area_increase(const SkIRect& rect1, SkIRect rect2) {
     join_no_empty_check(rect1, &rect2);
     return get_area(rect2) - get_area(rect1);