am: quote string for translation before passing to eval_gettextln

If it's not quoted, the string is expanded before it gets looked up in
gettext database and obviously nothing is returned.

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

git-am.sh

@@ -836,8 +836,8 @@ did you forget to use 'git add'?"
 		eval_gettextln 'Patch failed at $msgnum $FIRSTLINE'
 		if test "$(git config --bool advice.amworkdir)" != false
 		then
-			eval_gettextln "The copy of the patch that failed is found in:
-   $dotest/patch"
+			eval_gettextln 'The copy of the patch that failed is found in:
+   $dotest/patch'
 		fi
 		stop_here_user_resolve $this
 	fi