fix (some) 64bit warnings -- size_t -> int

src/core/SkError.cpp

Index: src/core/SkError.cpp
diff --git a/src/core/SkError.cpp b/src/core/SkError.cpp
index f5d233c6dafa82aca01754431b06ee508b97d0de..9e8ff2ddef01ff3fda1f5340f7a7e0f42713a796 100644
--- a/src/core/SkError.cpp
+++ b/src/core/SkError.cpp
@@ -130,7 +130,7 @@ void SkErrorInternals::SetError(SkError code, const char *fmt, ...) {
     }
 
     sprintf( str, "%s: ", error_name );
-    int string_left = ERROR_STRING_LENGTH - strlen( str );
+    int string_left = SkToInt(ERROR_STRING_LENGTH - strlen(str));
     str += strlen(str);
 
     va_start( args, fmt );