format-patch: remove applies-to.

The attempt to help 3-way fallback by recording the tree object
id for the entire pre-image was unnecessary, and we already have
an better alternative in the form of per-blob "index" lines.

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

git-format-patch.sh

@@ -238,7 +238,6 @@ Date: '"$ad"
 	echo
 	git-diff-tree -p $diff_opts "$commit" | git-apply --stat --summary
 	echo
-	git-cat-file commit "$commit^" | sed -e 's/^tree /applies-to: /' -e q
 	git-diff-tree -p $diff_opts "$commit"
 	echo "---"
 	echo "@@GIT_VERSION@@"