This is a continuation and modernization of https://github.com/gofed/go-macros/issues/35

When bootstrapping a set of Go projects, with circular dependencies, you need to identify quickly the parts that participate in the loop, so they can be culled in the initial bootstrap package

For example if docker-x depends directly or indirectly on docker-y, and docker-y imports docker-x in its own code (or tests), you want to identify the docker-x parts that use docker-y and remove them in %prep. And then, once the result is built, and permits an initial built of docker-y, you can use the resulting docker-y package to build docker-x without removing anything

This could be done by adding a -x --exclude-import-path switch to golist.

The switch can occur several times, to specify several exclusions in one pass, as some codebases participate in several loops at once