ARM Linux support

According to [this](https://github.com/HaxeFoundation/hxcpp/blob/master/hxcpp/Builder.hx#L124), ARM Linux isn't supported? (I do see mention of rpi and gcw0 in toolchains though, so I assume this isn't the whole story)

Is there anything needed here other than adding armv6/7/64 to the valid architecture list to change that?

Disclaimer: I am new to hxcpp, and have no idea how it works under the hood, just that I can't compile on my laptop.

EDIT: I've gotten a little further by adding -D noM32, but there are several build errors, is gcc 4.6 supported still?