Allow implicit-fallthrough warnings locally. DO NOT MERGE.

It will be a global error by default.
This change is not needed in goog/master.

Test: make checkbuild
Bug: 112564944
Change-Id: I8e47a4e077260f25bd588d786842548fcaa48634
Exempt-From-Owner-Approval: do not block on new warnings
diff --git a/libhwcomposer/Android.bp b/libhwcomposer/Android.bp
index 384e7e2..7857e48 100644
--- a/libhwcomposer/Android.bp
+++ b/libhwcomposer/Android.bp
@@ -30,6 +30,7 @@
         "-Wno-unused-parameter",
         "-Wno-missing-field-initializers",
         "-fexceptions",
+        "-Wno-implicit-fallthrough", // in format.cpp
     ],
 
     shared_libs: [