Running on Apple Silicon

[AdamGEmerson]

I ran into some issues running the library on Apple silicon due to the fact that gcc-6 only offers x_86 support.

I was able to fix this by modifying the Makefile to use gcc-12, which works for both mac and intel chips. I also had to remove the -msse2 flags, which appear to be related to Microsoft security features for Windows.

Perhaps we should update the readme to include information for Apple Silicon?