Use gralloc usage conversion library

Converting from ..graphics.allocator@2.0 usage to gralloc0 usage isn't
quite as simple as ORing and truncating, which is what the default
implementation was doing. Switch to using library functions that do it
correctly.

Test: boot bullhead
Change-Id: Ibe644b53655e191b9bca9d619825a8918e8fc365
diff --git a/libs/nativewindow/Android.bp b/libs/nativewindow/Android.bp
index 2668927..90fb4b6 100644
--- a/libs/nativewindow/Android.bp
+++ b/libs/nativewindow/Android.bp
@@ -53,6 +53,7 @@
 
     static_libs: [
         "libarect",
+        "libgrallocusage",
     ],
 
     // headers we include in our public headers