Include ref log detail in commit, reset, etc.

When updating a ref at the direction of the user include a reason why
head was changed as part of the ref log (assuming it was enabled).

Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Signed-off-by: Junio C Hamano <junkio@cox.net>

git-applypatch.sh

@@ -204,7 +204,7 @@ echo Wrote tree $tree
 parent=$(git-rev-parse --verify HEAD) &&
 commit=$(git-commit-tree $tree -p $parent <"$final") || exit 1
 echo Committed: $commit
-git-update-ref HEAD $commit $parent || exit
+git-update-ref -m "applypatch: $SUBJECT" HEAD $commit $parent || exit
 
 if test -x "$GIT_DIR"/hooks/post-applypatch
 then