Add shmem config buffer to libvrflinger

This allows VrCore to configure some tunable behaviors
of libvrflinger.

- Added dvrDisplayManagerDeleteNamedBuffer for testing config buffer
  creation.
- Added tests for named buffers, including one for the config buffer.
- Added IsValid to broadcast_ring to avoid tracking redundant state
  externally.

Bug: 38193993
Test: Run dvr_named_buffer-test
Change-Id: I52722dd314233b5bea1ca6377c14b5c856825746
diff --git a/libs/vr/libvrflinger/Android.bp b/libs/vr/libvrflinger/Android.bp
index d37031f..080479a 100644
--- a/libs/vr/libvrflinger/Android.bp
+++ b/libs/vr/libvrflinger/Android.bp
@@ -36,6 +36,7 @@
     "libvrsensor",
     "libpdx_default_transport",
     "libvr_manager",
+    "libbroadcastring",
 ]
 
 sharedLibraries = [
@@ -77,7 +78,7 @@
         "-DEGL_EGLEXT_PROTOTYPES",
     ],
     shared_libs: sharedLibraries,
-    header_libs: headerLibraries,
     whole_static_libs: staticLibraries,
+    header_libs: headerLibraries,
     name: "libvrflinger",
 }