Allow implicit-fallthrough warnings locally.

It will be a global error by default.

Test: make checkbuild
Bug: 112564944
Change-Id: I26616fd50ccf3639fa7c01d850a14d079273ede7
Exempt-From-Owner-Approval: do not block on new warnings
diff --git a/tools/incident_section_gen/Android.bp b/tools/incident_section_gen/Android.bp
index f07445a..0c7797e 100644
--- a/tools/incident_section_gen/Android.bp
+++ b/tools/incident_section_gen/Android.bp
@@ -24,6 +24,8 @@
         "-O0",
         "-Wall",
         "-Werror",
+        // Allow implicit fallthroughs in main.cpp until they are fixed.
+        "-Wno-error=implicit-fallthrough",
     ],
     srcs: ["main.cpp"],
     shared_libs: [