configure: enable -Wimplicit-fallthrough

* m4/gccwarn.m4: Here.

configure: enable -Wimplicit-fallthrough
* m4/gccwarn.m4: Here.
7ff50d89 · Alexandre Duret-Lutz · a5d6aa25 · 7ff50d89
Commit 7ff50d89 authored Oct 07, 2016 by Alexandre Duret-Lutz
--- a/m4/gccwarn.m4
+++ b/m4/gccwarn.m4
@@ -37,6 +37,7 @@ EOF
   Wnoexcept \
   Woverloaded-virtual \
   Wmisleading-indentation \
+   Wimplicit-fallthrough \
   Wlogical-op \
   Wduplicated-cond \
   Wnull-dereference \