git-add -i: update removed path correctly.

Earlier, when a path that was removed from the working tree was
chosen for update subcommand, you got an error like this:

    error: git-resolve.sh: does not exist and --remove not passed
    fatal: Unable to process file git-resolve.sh

Signed-off-by: Junio C Hamano <junkio@cox.net>

git-add--interactive.perl

@@ -1,6 +1,5 @@
 #!/usr/bin/perl -w
 
-
 use strict;
 
 sub run_cmd_pipe {
@@ -282,7 +281,7 @@ sub update_cmd {
 				       HEADER => $status_head, },
 				     @mods);
 	if (@update) {
-		system(qw(git update-index --add --),
+		system(qw(git update-index --add --remove --),
 		       map { $_->{VALUE} } @update);
 		say_n_paths('updated', @update);
 	}