Allow implicit-fallthrough warnings locally.

It will be a global error by default.
Cherry pick lost changes from AOSP, for Android.mk and main.cpp.

Test: make checkbuild
Bug: 112564944
Change-Id: I6f1024fa5e31302af27fa9d5bac195e511f4ba20
Exempt-From-Owner-Approval: do not block on new warnings
diff --git a/libs/hwui/Android.bp b/libs/hwui/Android.bp
index 503951d..f0053a4 100644
--- a/libs/hwui/Android.bp
+++ b/libs/hwui/Android.bp
@@ -231,6 +231,9 @@
         "protos/graphicsstats.proto",
     ],
 
+    // Allow implicit fallthroughs in HardwareBitmapUploader.cpp until they are fixed.
+    cflags: ["-Wno-implicit-fallthrough"],
+
     proto: {
         export_proto_headers: true,
     },