Blacklist a known failure in GregorianCalendarTest.

The issues here relate to how we deal with ambiguous wall
clock times, i.e, wall clock values that we "skip" when we
move the clock forward when transitioning into daylight
savings, and wall clock times that occur twice when we
move the clock backward

This isn't a regression. We've never handled this correctly.

bug: 12778197
Change-Id: Ida79583c02c6895096a8afdd8f59b1002b282d32
diff --git a/expectations/knownfailures.txt b/expectations/knownfailures.txt
index b0923e5..8bf1306 100644
--- a/expectations/knownfailures.txt
+++ b/expectations/knownfailures.txt
@@ -1655,5 +1655,10 @@
     "org.apache.harmony.tests.java.net.URLTest#test_sameFileLjava_net_URL",
     "org.apache.harmony.tests.java.net.URLDecoderTest#test_decodeLjava_lang_String_Ljava_lang_String"
   ]
+},
+{
+  description: "Known failure in GregorianCalendarTest",
+  bug: 12778197,
+  name: "org.apache.harmony.tests.java.util.GregorianCalendarTest#test_computeTime"
 }
 ]