[libhwc2on1adapter] Fix blueprint warnings

Change-Id: Ia6e726979ec7b549d9a2ba637b32dd0559869ee7
diff --git a/libs/hwc2on1adapter/Android.bp b/libs/hwc2on1adapter/Android.bp
index 2be3e67..438d3f5 100644
--- a/libs/hwc2on1adapter/Android.bp
+++ b/libs/hwc2on1adapter/Android.bp
@@ -48,6 +48,9 @@
         "-Wno-sign-conversion",
         "-Wno-switch-enum",
         "-Wno-float-equal",
+        "-Wno-shorten-64-to-32",
+        "-Wno-sign-compare",
+        "-Wno-missing-prototypes",
     ],
 
     srcs: [