Move some functions to MathPriv.h

Change-Id: I22c57a746e4a997fc03f35aa06b23d9fa9ed4fa9
Reviewed-on: https://skia-review.googlesource.com/152183
Commit-Queue: Hal Canary <halcanary@google.com>
Commit-Queue: Mike Klein <mtklein@google.com>
Auto-Submit: Hal Canary <halcanary@google.com>
Reviewed-by: Mike Klein <mtklein@google.com>
diff --git a/src/codec/SkBmpStandardCodec.cpp b/src/codec/SkBmpStandardCodec.cpp
index dd71535..8e01ac0 100644
--- a/src/codec/SkBmpStandardCodec.cpp
+++ b/src/codec/SkBmpStandardCodec.cpp
@@ -8,6 +8,7 @@
 #include "SkBmpStandardCodec.h"
 #include "SkCodecPriv.h"
 #include "SkColorData.h"
+#include "SkMathPriv.h"
 #include "SkStream.h"
 
 /*