Add ARM Thumb2 port #33
Description
This is relevant for the low-end Cortex-M CPUs that only support Thumb2 code. They simply can't run ARM32 machine code.
Even though mobile ARM CPUs are going the ARM64 route (which explicitly includes ARM32), the Cortex-M SoCs are not going away. Most of them have enough internal memory to run LuaJIT and they're quite popular due to their low cost.
This needs a DynASM Thumb2 port, a port of the interpreter and a new JIT compiler backend.
Beginnings of this can be found at: https://github.com/tcr/luajit
But this work has apparently been abandoned and never submitted upstream. It's interwoven with unrelated support code for their JS to Lua transpiler. It looks incomplete, too. It needs significant cleanup and/or rewriting.