add arm-eabi 4.8 for kernel and linux-androideabi 4.9 to test rom compile

export TARGET_GCC_VERSION=4.9 to compile rom with 4.9 (needs fixes)

export TARGET_KERNEL_CUSTOM_TOOLCHAIN=arm-eabi-4.8/bin/arm-eabi- to compile kernel with 4.8. Works for xt926 currently