[sledge] Add handler for Ctrl-C

Summary: so that we get a backtrace.

Reviewed By: da319

Differential Revision: D24746240

fbshipit-source-id: b76be5a82

sledge/cli/sledge_cli.ml

@@ -271,6 +271,8 @@ let readme () =
 
 ;;
 Printexc.record_backtrace Version.debug
+;;
+Stdlib.Sys.catch_break true
 
 ;;
 Command.run ~version:Version.version ~build_info:Version.build_info