Int key for the named buffers.

Also, rename them to global buffers from named buffers.

Bug: 38320428
Test: Run frameworks/native/libs/vr/libdvr/tests on device
Change-Id: I2109aea77e35f2ccd8055208058df4b7287c1d5e
diff --git a/libs/vr/libdisplay/Android.bp b/libs/vr/libdisplay/Android.bp
index d90521a..c0c7e2f 100644
--- a/libs/vr/libdisplay/Android.bp
+++ b/libs/vr/libdisplay/Android.bp
@@ -45,6 +45,7 @@
 
 headerLibraries = [
     "vulkan_headers",
+    "libdvr_headers",
 ]
 
 cc_library {