add --csv parameter to skpdiff to dump all scores in a csv file. We can run it with all skps, and h…

experimental/skpdiff/SkDiffContext.h

Index: experimental/skpdiff/SkDiffContext.h
===================================================================
--- experimental/skpdiff/SkDiffContext.h	(revision 10232)
+++ experimental/skpdiff/SkDiffContext.h	(working copy)
@@ -90,6 +90,12 @@
      */
     void outputRecords(SkWStream& stream, bool useJSONP);
 
+    /**
+     * Output the records score in csv format.
+     */
+    void outputCsv(SkWStream& stream);
+
+
 private:
     struct DiffData {
         const char* fDiffName;