mailsplit: remove unnecessary unlink(2) call

The output file hasn't been created at this point, yet, so there is no
need to delete it when exiting early.

Suggested-by: Jeff King <peff@peff.net>
Signed-off-by: Rene Scharfe <l.s.r@web.de>
Reviewed-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin/mailsplit.c

@@ -59,7 +59,6 @@ static int split_one(FILE *mbox, const char *name, int allow_bare)
 	int is_bare = !is_from_line(buf.buf, buf.len);
 
 	if (is_bare && !allow_bare) {
-		unlink(name);
 		fprintf(stderr, "corrupt mailbox\n");
 		exit(1);
 	}