Fix /bin/bash shebangs

Summary:
"/bin/bash" is a Linuxism.  "/usr/bin/env bash" is portable.
Closes https://github.com/facebook/rocksdb/pull/2646

Differential Revision: D5556259

Pulled By: ajkr

fbshipit-source-id: cbffd38ecdbfffb2438969ec007ab345ed893ccb

buckifier/rocks_test_runner.sh

-#!/bin/bash
+#!/usr/bin/env bash
 # Create a tmp directory for the test to use
 TEST_DIR=$(mktemp -d /dev/shm/fbcode_rocksdb_XXXXXXX)
 TEST_TMPDIR="$TEST_DIR" $@ && rm -rf "$TEST_DIR"

build_tools/cont_integration.sh

-#!/bin/bash
+#!/usr/bin/env bash
 #
 # Copyright (c) 2016, Facebook. All rights reserved.
 #

build_tools/dockerbuild.sh

-#!/bin/bash
+#!/usr/bin/env bash
 docker run -v $PWD:/rocks -w /rocks buildpack-deps make

build_tools/format-diff.sh

-#!/bin/bash
+#!/usr/bin/env bash
 # If clang_format_diff.py command is not specfied, we assume we are able to
 # access directly without any path.
 if [ -z $CLANG_FORMAT_DIFF ]

build_tools/regression_build_test.sh

-#!/bin/bash
+#!/usr/bin/env bash
 
 set -e
 

build_tools/rocksdb-lego-determinator

-#!/bin/bash
+#!/usr/bin/env bash
 # This script is executed by Sandcastle
 # to determine next steps to run
 

coverage/coverage_test.sh

-#!/bin/bash
+#!/usr/bin/env bash
 
 # Exit on error.
 set -e

tools/benchmark.sh

-#!/bin/bash
+#!/usr/bin/env bash
 # REQUIRE: db_bench binary exists in the current directory
 
 if [ $# -ne 1 ]; then

tools/benchmark_leveldb.sh

-#!/bin/bash
+#!/usr/bin/env bash
 # REQUIRE: db_bench binary exists in the current directory
 #
 # This should be used with the LevelDB fork listed here to use additional test options.

tools/check_format_compatible.sh

-#!/bin/bash
+#!/usr/bin/env bash
 #
 # A shell script to load some pre generated data file to a DB using ldb tool
 # ./ldb needs to be avaible to be executed.

tools/dbench_monitor

-#!/bin/bash
+#!/usr/bin/env bash
 #
 #(c) 2004-present, Facebook Inc. All rights reserved.
 #

tools/generate_random_db.sh

-#!/bin/bash
+#!/usr/bin/env bash
 #
 # A shell script to load some pre generated data file to a DB using ldb tool
 # ./ldb needs to be avaible to be executed.

tools/pflag

-#!/bin/bash
+#!/usr/bin/env bash
 #
 #(c) 2004-present, Facebook, all rights reserved. 
 # See the LICENSE file for usage and distribution rights.

tools/rdb/rdb

-#!/bin/bash
+#!/usr/bin/env bash
 
 node -e "RDB = require('./build/Release/rdb').DBWrapper; console.log('Loaded rocksdb in variable RDB'); repl = require('repl').start('> ');"

tools/regression_test.sh

-#!/bin/bash
+#!/usr/bin/env bash
 # The RocksDB regression test script.
 # REQUIREMENT: must be able to run make db_bench in the current directory
 #

tools/run_flash_bench.sh

-#!/bin/bash
+#!/usr/bin/env bash
 # REQUIRE: benchmark.sh exists in the current directory
 # After execution of this script, log files are generated in $output_dir.
 # report.txt provides a high level statistics

tools/run_leveldb.sh

-#!/bin/bash
+#!/usr/bin/env bash
 # REQUIRE: benchmark_leveldb.sh exists in the current directory
 # After execution of this script, log files are generated in $output_dir.
 # report.txt provides a high level statistics

tools/verify_random_db.sh

-#!/bin/bash
+#!/usr/bin/env bash
 #
 # A shell script to verify DB generated by generate_random_db.sh cannot opened and read correct data.
 # ./ldb needs to be avaible to be executed.