Makefile support ARM linux

[seanshpark]

Hi,
I'm adding this issue as a todo item to support arm-linux and with maybe add other architecture-platform easier. And as there is no issue, I want to start with this not-urgent one.

• platforms that we can support: linux, nuttx, darwin, ...
• architectures: armv7, armv6, i686, x86_64, ...
• type: debug, release, ...
• mods: cp cp_minimal, mem_stats, ...
• boards (maybe for embedded): stm32f3, stm32f4, ...

[egavrin]

//Note to self: We need to provide a simple way of adding new toolchain configurations

[egavrin]

Cross compilation support added 444bd32

[seanshpark]

Thank you!
I've checked with arm-linux-eabi-gcc version 4.7 build with

make debug.linux TOOLCHAIN=./build/configs/toolchain_linux_armv7l-el.cmake

with 71bac03 (as of 1 July) and got this problem;

jerry-core/lit/lit-strings.cpp:378:81: error: conversion to ‘lit_utf8_byte_t {aka unsigned char}’ from ‘int’ may alter its value [-Werror=conversion]

[egavrin]

@seanshpark I'll check. Thank you!

[egavrin]

@seanshpark please check #291

[seanshpark]

@egavrin thank you, I'll wait #291 to land.