Add fmtlib to hwasan-postsubmit. am: be3d771f0c am: c6a4818bc8

Original change: https://android-review.googlesource.com/c/platform/external/fmtlib/+/2028806

Change-Id: I0a149985bb6f560664f38502060b23cec1d8128e
diff --git a/TEST_MAPPING b/TEST_MAPPING
index caeecd6..328028d 100644
--- a/TEST_MAPPING
+++ b/TEST_MAPPING
@@ -6,5 +6,13 @@
     {
       "name": "fmtlib_ostream_test"
     }
+  ],
+  "hwasan-postsubmit": [
+    {
+      "name": "fmtlib_test"
+    },
+    {
+      "name": "fmtlib_ostream_test"
+    }
   ]
 }