support 32-bit

[anonymouse64]

All of the code + Makefile is currently 64-bit specific, we should also support armhf too, so that this works on i.e. the Raspberry Pi 2 which does not support arm64.

[anonymouse64]

some examples from the same original author in a different project: https://gitlab.com/bztsrc/imgrecv/-/tree/master/raspi