mfc_candidates: remove leftover message

When I first converted mfc-candidates to Lua I did not implement -X
(exclude file), and just emitted a message that -X wasn't implemented.
Support was implemented before I pushed the change but I forgot to
remove the message.

Fixes: 48f3fca ("mfc-candidates: Convert to Lua")
Sponsored by: The FreeBSD Foundation

tools/tools/git/mfc-candidates.lua

@@ -176,7 +176,6 @@ local function main()
 			verbose = verbose + 1
 		elseif opt == "-X" then
 			exclude_file = arg[i + 1]
-			print ("-X not working")
 			i = i + 1
 		else
 			break