fix warnings around size_t/int

src/core/SkDistanceFieldGen.cpp

Index: src/core/SkDistanceFieldGen.cpp
diff --git a/src/core/SkDistanceFieldGen.cpp b/src/core/SkDistanceFieldGen.cpp
index aec5f1d13eeaf328c9ef5d7ea82dff3ba0f30bb3..ef0ee86d59ce7731f36f4be401d1777d659a8f07 100755
--- a/src/core/SkDistanceFieldGen.cpp
+++ b/src/core/SkDistanceFieldGen.cpp
@@ -329,9 +329,9 @@ static unsigned char pack_distance_field_val(float dist, float distanceMagnitude
 
 // assumes a padded 8-bit image and distance field
 // width and height are the original width and height of the image
-bool generate_distance_field_from_image(unsigned char* distanceField,
-                                        const unsigned char* copyPtr,
-                                        int width, int height) {
+static bool generate_distance_field_from_image(unsigned char* distanceField,
+                                               const unsigned char* copyPtr,
+                                               int width, int height) {
     SkASSERT(NULL != distanceField);
     SkASSERT(NULL != copyPtr);