Cross-compiling for M1 mac from non-M1 mac

[jmgomez]

In NimForUE we compile one of the dynlibs for x86 and ARM and then we unify it 
with lipo. Didnt test it from x86 but it works fine from a M1. Here is the code 
in case you want to take a look:

<https://github.com/jmgomez/NimForUE/blob/b696634d29784569f62d7c26c852a7e800f63d60/src/buildscripts/nuecompilation/nuecompilation.nim#L12>