llvmPackages.clang-tools: use correct shell shebang

This wrapper is factually a bash script and should therefore use the
correct shebang instead of relying on the leniency of the bash POSIX
mode.

pkgs/development/compilers/llvm/common/clang-tools/wrapper

@@ -1,4 +1,4 @@
-#!/bin/sh
+#!/usr/bin/env bash
 
 buildcpath() {
   local path after