utils/rebind, utils/u2x11: use /usr/bin/env

utils/rebind

@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/usr/bin/env bash
 
 usage() {
     echo "Usage: $(basename $0) OLD_PORT NEW_PORT COMMAND_LINE"

utils/u2x11

@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/usr/bin/env bash
 #
 # Convert "U+..." commented entries in /usr/include/X11/keysymdef.h
 # into JavaScript for use by noVNC.  Note this is likely to produce