Add support for macOS Intel (x86_64)

[jamesmaa]

Hi! It would be cool to have a macOS Intel (x86_64) build of zb for folks like me who have older Mac hardware not on Apple Silicon yet.

Current output:

❯ ./install
Testing for password-less sudo...
Success. Running as root.
Ctrl-C to stop the install process if this is not what you meant to do.
Creating /opt/zb/store...
Initializing store database...
./install: line 204: /opt/zb/store/47ywadxdyzmv15aa3pl5mq2l47hpp0z8-zb-0.1.0/bin/zb: cannot execute binary file
❯ file /opt/zb/store/47ywadxdyzmv15aa3pl5mq2l47hpp0z8-zb-0.1.0/bin/zb
/opt/zb/store/47ywadxdyzmv15aa3pl5mq2l47hpp0z8-zb-0.1.0/bin/zb: ELF 64-bit LSB executable, x86-64, version 1 (SYSV), statically linked, BuildID[sha1]=68a1efc0cbfaedbf8c23b6480433ae64e1358659, stripped