test klayout macosx packages

[proppy]

@njcoburn offered to test the recent work on macosx packages.

putting some instructions there for testing:

• install miniconda in a new environment https://docs.conda.io/projects/continuumio-conda/en/latest/user-guide/install/macos.html
• run the following command:

  source silicon-macosx-env/bin/activate
  conda install -c litex-hub klayout magic openlane open_pdks.gf180mcuc
  bash ~/Downloads/mixed-signal.gf180mcuc-0-Linux-x86_64.sh -b -p silicon-env/
  source silicon-env/bin/activate
  klayout -v
  yosys --version
  openroad -version
  netgen -batch quit
  magic -dnull -noconsole --version
  echo exit | flow.tcl -interactive # openlane

[njcoburn]

@proppy I finally got back to trying this on my personal Mac M1. I am not getting past here...

PREFIX=/Users/njcoburn/opt/anaconda3/envs/myenv/silicon-env
/Users/njcoburn/Downloads/mixed-signal.gf180mcuc-0-Linux-x86_64.sh: line 213: md5sum: command not found