Add comment to cctest status file.

test/cctest/cctest.status

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 prefix cctest
 
+# All tests prefixed with 'Bug' are expected to fail.
 test-api/Bug*: FAIL
 
 ##############################################################################
 # BUG(382): Weird test. Can't guarantee that it never times out.
 test-api/ApplyInterruption: PASS || TIMEOUT
 
 # BUG(484): This test which we thought was originally corrected in r5236
 # is re-appearing. Disabled until bug in test is fixed. This only fails
 # when snapshot is on, so I am marking it PASS || FAIL
 test-heap-profiler/HeapSnapshotsDiff: PASS || FAIL
@@ skipping 42 matching lines @@
 test-debug/ThreadedDebugging: SKIP
 test-debug/DebugBreakLoop: SKIP
 
 
 ##############################################################################
 [ $arch == mips && $crankshaft ]
 
 # Tests that time out with crankshaft.
 test-debug/ThreadedDebugging: SKIP
 test-debug/DebugBreakLoop: SKIP