Replace SkConsistentChecksum with SkCityHash (now including CityHash via DEPS)

Alternative to https://codereview.appspot.com/6847087/ ('Change SkConsistentChecksum to use SuperFastHash')
Review URL: https://codereview.appspot.com/6867060

git-svn-id: http://skia.googlecode.com/svn/trunk@6701 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/DEPS b/DEPS
index 55a6401..5cd2370 100644
--- a/DEPS
+++ b/DEPS
@@ -9,6 +9,7 @@
 #
 deps = {
   "third_party/externals/angle" : "http://angleproject.googlecode.com/svn/trunk@1268",
+  "third_party/externals/cityhash" : "http://cityhash.googlecode.com/svn/trunk@11",
   "third_party/externals/freetype" : "https://android.googlesource.com/platform/external/freetype.git",
   "third_party/externals/gyp" : "http://gyp.googlecode.com/svn/trunk@1517",
   "third_party/externals/libjpeg" : "http://src.chromium.org/svn/trunk/src/third_party/libjpeg@125399",