Make rushlink script more portable.

It didn't work on mac (and bsd, probably). Now it does.

contrib/rushlink

@@ -13,7 +13,7 @@ link() {
         *)
             curl -sS -Ffile=@- "$LINK" < "$1"
             ;;
-    esac | sed -n '1p;/deleteToken/{s@.*\(https://\)@\1@;p;q}' | (
+    esac | awk 'NR == 1 { print } $NF ~ /deleteToken=/ { print $NF; exit }' | (
         IFS= read -r link
         IFS= read -r deletelink
         echo "$link"