fix broken build on mac due to compiler warning

R=epoger@google.com

Review URL: https://codereview.chromium.org/64423004

git-svn-id: http://skia.googlecode.com/svn/trunk@12175 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/tools/skpdiff/SkImageDiffer.cpp b/tools/skpdiff/SkImageDiffer.cpp
index 8a5c3c7..40a34da 100644
--- a/tools/skpdiff/SkImageDiffer.cpp
+++ b/tools/skpdiff/SkImageDiffer.cpp
@@ -11,6 +11,8 @@
 #include "SkImageDiffer.h"
 #include "skpdiff_util.h"
 
+const double SkImageDiffer::RESULT_CORRECT = 1.0f;
+const double SkImageDiffer::RESULT_INCORRECT = 0.0f;
 
 SkImageDiffer::SkImageDiffer()
     : fIsGood(true) {
diff --git a/tools/skpdiff/SkImageDiffer.h b/tools/skpdiff/SkImageDiffer.h
index 3b50d57..2c1fa7e 100644
--- a/tools/skpdiff/SkImageDiffer.h
+++ b/tools/skpdiff/SkImageDiffer.h
@@ -19,8 +19,8 @@
     SkImageDiffer();
     virtual ~SkImageDiffer();
 
-    static const double RESULT_CORRECT = 1.0f;
-    static const double RESULT_INCORRECT = 0.0f;
+    static const double RESULT_CORRECT;
+    static const double RESULT_INCORRECT;
 
     /**
      * Gets a unique and descriptive name of this differ