Add CtsBionicAppTestCases to postsubmit

We can't add CtsBionicAppTestCases to presubmit (my actual goal here)
until it's been in postsubmit.

Test: treehugger
Change-Id: Iff872b99cfcaf6c92f98e37ade782ad3ae55cd8b
diff --git a/TEST_MAPPING b/TEST_MAPPING
index f56e16a..9304013 100644
--- a/TEST_MAPPING
+++ b/TEST_MAPPING
@@ -88,5 +88,10 @@
     {
       "name": "CtsBionicTestCases"
     }
+  ],
+  "postsubmit": [
+    {
+      "name": "CtsBionicAppTestCases"
+    }
   ]
 }