* lint: expand to src/{os,reflect}, fix or suppress what it found
* internal/tools/tools.go: the tools idiom requires a build tag guard to avoid go test complaints
See https://github.com/tinygo-org/tinygo/issues/4225
Runs in both circleci and github, circleci is run on branch push, github is run on PR
Revive builds so fast, don't bother installing it; saves us wondering which one we get
Uses tools.go idiom to give control over linter versions to go.mod.
Also pacifies linter re AppendToGlobal as a token first fix.
TODO: gradually expand the number of directories that are linted,
uncomment more entries in revive.toml, and fix or suppress the
warnings lint finds.
TODO: add linters "go vet" and staticcheck
NOT TODO: don't add metalinters like golangci-lint that pull in
lots of new of dependencies; we'd rather not clutter go.mod that
much, let alone open ourselves up to the additional attack surface.
dkegel-fastly
Dan Kegel