building sigrok-cli on macOS 10.13.6

[ipatch]

Heads up, I tried installing sigrok-cli this afternoon with

brew install sigrok-cli

after tapping this repo, and ran into an issue where the homebrew install process could not find the opt dir for doxygen, or the formula for sigrok-cli was looking for doxygen in a path that did not exist on my box.

All that said, the quick hack / fix was to create a symlink so the installer, ie.

brew install sigrok-cli

could find the necessary doxygen deps to complete the installation.

ln -sf /usr/local/Cellar/doxygen /usr/local/opt/doxygen

allowed me to successfully install sigrok-cli