Remove third-party cityhash, unused since r8992

gm/gm_expectations.cpp

Index: gm/gm_expectations.cpp
===================================================================
--- gm/gm_expectations.cpp	(revision 9056)
+++ gm/gm_expectations.cpp	(working copy)
@@ -16,18 +16,10 @@
 const static char kJsonKey_ActualResults_FailureIgnored[]= "failure-ignored";
 const static char kJsonKey_ActualResults_NoComparison[]  = "no-comparison";
 const static char kJsonKey_ActualResults_Succeeded[]     = "succeeded";
-#ifdef BITMAPHASHER_USES_TRUNCATED_MD5
 const static char kJsonKey_ActualResults_AnyStatus_BitmapHash[]  = "bitmap-64bitMD5";
-#else
-const static char kJsonKey_ActualResults_AnyStatus_BitmapHash[]  = "bitmap-cityhash";
-#endif
 
 const static char kJsonKey_ExpectedResults[] = "expected-results";
-#ifdef BITMAPHASHER_USES_TRUNCATED_MD5
 const static char kJsonKey_ExpectedResults_AllowedBitmapHashes[] = "allowed-bitmap-64bitMD5s";
-#else
-const static char kJsonKey_ExpectedResults_AllowedBitmapHashes[] = "allowed-bitmap-cityhashes";
-#endif
 const static char kJsonKey_ExpectedResults_IgnoreFailure[]           = "ignore-failure";
 
 namespace skiagm {