Fix envsetup.sh to be zsh friendly.

build/android/envsetup.sh

 #!/bin/bash
 # Copyright (c) 2012 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 # Sets up environment for building Chromium on Android.  It can either be
 # compiled with the Android tree or using the Android SDK/NDK. To build with
 # NDK/SDK: ". build/android/envsetup.sh".  Environment variable
 # ANDROID_SDK_BUILD=1 will then be defined and used in the rest of the setup to
 # specifiy build type.
@@ skipping 127 matching lines @@
 fi
 
 # Source a bunch of helper functions
 . ${CHROME_SRC}/build/android/adb_device_functions.sh
 
 ANDROID_GOMA_WRAPPER=""
 if [[ -d $GOMA_DIR ]]; then
   ANDROID_GOMA_WRAPPER="$GOMA_DIR/gomacc"
   num_cores="$(grep --count ^processor /proc/cpuinfo)"
 # Goma is IO-ish you want more threads than you have cores.
-  let goma_threads=num_cores*2
+  let "goma_threads=num_cores*2"
   if [ -z "${GOMA_COMPILER_PROXY_THREADS}" -a "${goma_threads}" -gt 16 ]; then
 # The default is 16 threads, if the machine has many cores we crank it up a bit
     GOMA_COMPILER_PROXY_THREADS="${goma_threads}"
     export GOMA_COMPILER_PROXY_THREADS
   fi
 fi
 export ANDROID_GOMA_WRAPPER
 
 # Declare Android are cross compile.
 export GYP_CROSSCOMPILE=1
 
 # Performs a gyp_chromium run to convert gyp->Makefile for android code.
 android_gyp() {
   # This is just a simple wrapper of gyp_chromium, please don't add anything
   # in this function.
   echo "GYP_GENERATORS set to '$GYP_GENERATORS'"
   (
     "${CHROME_SRC}/build/gyp_chromium" --depth="${CHROME_SRC}" --check "$@"
   )
 }
 
 # FLOCK needs to be null on system that has no flock
 which flock > /dev/null || export FLOCK=