Build the gatekeeper tests with coverage flags.

Build gatekeeper test with coverage so that coverage can be measured
on coverage runs.

Test: make
Bug: 32021941
Change-Id: I61ad6e975875b3d5f12abe922a81bdff641db5fb
diff --git a/gatekeeper/1.0/vts/functional/Android.bp b/gatekeeper/1.0/vts/functional/Android.bp
index 9c72b81..e79e40e 100644
--- a/gatekeeper/1.0/vts/functional/Android.bp
+++ b/gatekeeper/1.0/vts/functional/Android.bp
@@ -31,7 +31,11 @@
     ],
     static_libs: ["libgtest"],
     cflags: [
+        "--coverage",
         "-O0",
         "-g",
     ],
+    ldflags: [
+        "--coverage"
+    ]
 }