Enable some runtime sanity checks when using at least gcc 4.9

Change-Id: I33208d4c27a27fb9222577ca176357035eeb7ba1
Reviewed-on: https://code.wireshark.org/review/5150
Reviewed-by: Jörg Mayer <jmayer@loplof.de>

CMakeLists.txt

@@ -234,6 +234,11 @@ else()
 		-fwrapv
 		-fno-strict-overflow
 		-fno-delete-null-pointer-checks
+		-fsanitize=undefined # compile and runtime checks
+		# -fsanitize=float-divide-by-zero
+		# -fsanitize=float-cast-overflow
+		# -fsanitize=address
+		# -fno-sanitize-recover # Abort during runtime
 		-Wvla
 		-Waddress
 		-Wattributes