Reserve 'libhidl' w/ convenient use.

I still accidentally type 'm libhidl' when trying to build test
libhidl. Might as well reserve the name and make that work.

Bug: N/A
Test: m libhidl
Change-Id: I093e18db347bad72aaa47aac2dbb045f50c9641d
diff --git a/Android.bp b/Android.bp
index 97ed108..4bd5eb3 100644
--- a/Android.bp
+++ b/Android.bp
@@ -22,6 +22,14 @@
     ],
 }
 
+phony {
+    name: "libhidl",
+    required: [
+        "libhidlbase",
+        "libhidltransport",
+    ],
+}
+
 cc_test {
     name: "libhidl_test",
     defaults: ["libhidl-defaults"],