Build target-side NFC test with coverage.

Instrument NFC test with coverage so that coverage can be collected
on NFC implementation.

Test: make vts
Change-Id: I30c082198a027bc02ecaaf3232ce5935010b398d
diff --git a/nfc/1.0/vts/functional/Android.bp b/nfc/1.0/vts/functional/Android.bp
index 0f9eb3d..021f7c1 100644
--- a/nfc/1.0/vts/functional/Android.bp
+++ b/nfc/1.0/vts/functional/Android.bp
@@ -31,7 +31,11 @@
     ],
     static_libs: ["libgtest"],
     cflags: [
+        "--coverage",
         "-O0",
         "-g",
     ],
+    ldflags: [
+        "--coverage"
+    ]
 }