make svndiff.py executable



git-svn-id: http://skia.googlecode.com/svn/trunk@9969 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/tools/svndiff.py b/tools/svndiff.py
old mode 100644
new mode 100755
index d8beb8d..4759bed
--- a/tools/svndiff.py
+++ b/tools/svndiff.py
@@ -1,3 +1,4 @@
+#!/usr/bin/python
 '''
 Generates a visual diff of all pending changes in the local SVN checkout.