Do not output XFAIL/XPASS.

The parser for treehugger does not understand these output values and
they are hard to understand.

Also, add a list description to make it clear what tests are failing and
why.

Test: Unit tests pass.
Test: Verify that bionic unit tests pass in treehugger.
Change-Id: I7911f96c5e7f9270ea97038435502bbd79d65d66
diff --git a/Test.cpp b/Test.cpp
index 3e345e9..5fbaa67 100644
--- a/Test.cpp
+++ b/Test.cpp
@@ -78,18 +78,14 @@
   }
 
   switch (result_) {
+    case TEST_XFAIL:
     case TEST_PASS:
       ColoredPrintf(COLOR_GREEN, "[    OK    ]");
       break;
     case TEST_XPASS:
-      ColoredPrintf(COLOR_RED, "[  XPASS   ]");
-      break;
     case TEST_FAIL:
       ColoredPrintf(COLOR_RED, "[  FAILED  ]");
       break;
-    case TEST_XFAIL:
-      ColoredPrintf(COLOR_YELLOW, "[  XFAIL   ]");
-      break;
     case TEST_TIMEOUT:
       ColoredPrintf(COLOR_RED, "[ TIMEOUT  ]");
       break;