Support MacOS M1 / Arm64

[evensonic]

Trying to install on a new Mac with M1 processor.

Successfully installed nix. However, when I try to install mcd-cli, it fails:

error: linking with `/nix/store/j8k53qm6d0q8vjy7rqv007c63pn0pnnf-clang-wrapper-5.0.2/bin/cc` failed: exit code: 1
...
note: ld: file not found: /usr/lib/system/libcache.dylib for architecture x86_64
          clang-5.0: error: linker command failed with exit code 1 (use -v to see invocation)

Looks like it assumes x86_64. Is there a way to install with arm64?