Add "gitk" to the list of scripts to be installed automatically.

Btw, it's fun just looking at the merged git repository itself with
gitk, now that it has two "roots".

Makefile

@@ -24,7 +24,7 @@ SCRIPTS=git git-apply-patch-script git-merge-one-file-script git-prune-script \
 	git-pull-script git-tag-script git-resolve-script git-whatchanged \
 	git-deltafy-script git-fetch-script git-status-script git-commit-script \
 	git-log-script git-shortlog git-cvsimport-script git-diff-script \
-	git-reset-script git-add-script git-checkout-script
+	git-reset-script git-add-script git-checkout-script gitk
 
 PROG=   git-update-cache git-diff-files git-init-db git-write-tree \
 	git-read-tree git-commit-tree git-cat-file git-fsck-cache \