[scripts,egs] Fix shebangs on bash scripts to #!/usr/bin/env bash, for portability (#3881)

Author: esdeboer

egs/aidatatang_200zh/s5/local/chain/compare_wer.sh

@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/usr/bin/env bash
 # Copyright 2018  Emotech LTD (Author: Xuechen Liu)
 
 # compare wer between diff. models in aidatatang_200zh chain directory

egs/aidatatang_200zh/s5/local/chain/tuning/run_tdnn_1a.sh

@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/usr/bin/env bash
 
 # This script is based on run_tdnn_7h.sh in swbd chain recipe.