coreir installation is failing when installing fault/mantle

[rdaly525]

https://travis-ci.com/cdonovick/peak/builds/121799226

[leonardt]

The new static build flow is broken because libverilogAST doesn't support static builds yet. I will fix this, but I will also update the default install instructions to have coreir installed before pycoreir, and if not, have it build/install the non-static version by default, and hide the static build behind a build from source option (I will look into releasing a static version on pypi but it may have to be a separate package, e.g. coreir-static because I can't seem to find a simple way to use the [option] syntax with an external build like this)