Add SK_API to global scope operators of SkMatrix

include/core/SkMatrix.h

Index: include/core/SkMatrix.h
diff --git a/include/core/SkMatrix.h b/include/core/SkMatrix.h
index 34f16077a45839b96447fbe380eb29feb61bdd99..a6edc1804fba2b0916056b8ae140290e74863629 100644
--- a/include/core/SkMatrix.h
+++ b/include/core/SkMatrix.h
@@ -539,8 +539,8 @@ public:
         return 0 == memcmp(fMat, m.fMat, sizeof(fMat));
     }
 
-    friend bool operator==(const SkMatrix& a, const SkMatrix& b);
-    friend bool operator!=(const SkMatrix& a, const SkMatrix& b) {
+    friend SK_API bool operator==(const SkMatrix& a, const SkMatrix& b);
+    friend SK_API bool operator!=(const SkMatrix& a, const SkMatrix& b) {
         return !(a == b);
     }