Add gtest_extras to hwasan-postsubmit am: 2445aa4669 am: f6c45f4524 am: f7c2bf2d3e

Original change: https://android-review.googlesource.com/c/platform/system/testing/gtest_extras/+/2032743

Change-Id: I8509f77652029ac1126a54069ef0f019a5a383d5
diff --git a/TEST_MAPPING b/TEST_MAPPING
index c4002f2..90cb945 100644
--- a/TEST_MAPPING
+++ b/TEST_MAPPING
@@ -3,5 +3,10 @@
     {
       "name": "gtest_isolated_tests"
     }
+  ],
+  "hwasan-postsubmit": [
+    {
+      "name": "gtest_isolated_tests"
+    }
   ]
 }