am: simplify "sq" function by using "git rev-parse --sq-quote"

Signed-off-by: Christian Couder <chriscool@tuxfamily.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

git-am.sh

@@ -44,11 +44,7 @@ else
 fi
 
 sq () {
-	for sqarg
+	git rev-parse --sq-quote "$@"
-	do
-		printf "%s" "$sqarg" |
-		sed -e 's/'\''/'\''\\'\'''\''/g' -e 's/.*/ '\''&'\''/'
-	done
 }
 
 stop_here () {