Easily select toolchain between 64bit and 32 bit kernel builds for Android

setupenv

#/bin/bash
#
# Download toolschains:
# git clone https://android.googlesource.com/platform/prebuilts/gcc/linux-x86/arm/arm-eabi-4.7 toolchain
# git clone https://android.googlesource.com/platform/prebuilts/gcc/linux-x86/aarch64/aarch64-linux-android-4.9 -b  marshmallow-release toolchain64
#
# Instructions to set toolchain for build:
# source setupenv 64

case "$1" in
  "32")
    echo "Setting build architecture to 32 bit (arm)"
    export ARCH=arm
    export SUBARCH=arm
    export CROSS_COMPILE=`pwd`/toolchain/bin/arm-eabi-
    ;;
  "64")
    echo "Setting build architecture to 64 bit (arm64)"
    export ARCH=arm64
    export SUBARCH=arm64
    export CROSS_COMPILE=`pwd`/toolchain64/bin/aarch64-linux-android-
    ;;
  *)
    echo "Pass either 32 or 64 bit"
    exit 1
    ;;
esac