Add GCC7 -Wimplicit-fallthrough support/fixes.

GCC7 will have a new -Wimplicit-fallthrough warning. It did catch one
small buglet in elflint option procession. So it seems useful to enable
to make sure all swatch case fallthroughs are deliberate.

Add configure check to detect whether gcc support -Wimplicit-fallthrough
and enable it. Add fixes and explicit fallthrough comments where necessary.

Signed-off-by: Mark Wielaard <[email protected]>

1 files changed, 6 insertions, 1 deletions

diff --git a/ChangeLog b/ChangeLog
index 8d615721..f21421f9 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,4 +1,9 @@
-2015-10-11  Akihiko Odaki  <[email protected]>
+2016-11-02  Mark Wielaard  <[email protected]>
+
+	* configure.ac: Add check for whether gcc accepts
+	-Wimplict-fallthrough.
+
+2016-10-11  Akihiko Odaki  <[email protected]>
 
 	* configure.ac: Add memrchr, rawmemchr and powerof2 checks.