Make skia almost compile again with clang.

src/core/SkXfermode.cpp

Index: src/core/SkXfermode.cpp
diff --git a/src/core/SkXfermode.cpp b/src/core/SkXfermode.cpp
index ac5cee4e3592954ba4b8c34e558652fba054934d..675e5caa442101816694ea61b3aa09423f269b2d 100644
--- a/src/core/SkXfermode.cpp
+++ b/src/core/SkXfermode.cpp
@@ -61,13 +61,6 @@ static inline int clamp_div255round(int prod) {
     }
 }
 
-static inline int clamp_max(int value, int max) {
-    if (value > max) {
-        value = max;
-    }
-    return value;
-}
-
 ///////////////////////////////////////////////////////////////////////////////
 
 //  kClear_Mode,    //!< [0, 0]