lint-install breaks on projects where Go programs exist in subdirectories

[tstromberg]

When run against hook, lint-install creates a bad Makefile:

% make lint
out/linters/golangci-lint-v1.42.0 run
ERRO Running error: context loading failed: no go files to analyze 
make: *** [lint] Error 5

That's because the Go modules live in two subdirectories:

% find . -name "go.mod"
./tink-docker/go.mod
./bootkit/go.mod

What should the Makefile generator do then? Probably something like:

• find each go.mod
• Have the rule cd into each directory and run golangci-lint -c ../.golangci.yaml

[tstromberg]

The right incantation seems to be:

find . -name go.mod | xargs -n1 dirname | xargs -n1 -I{} sh -c "cd {} && golangci-lint run -c $(GOLINT_CONFIG)"

We can use that for projects that lack a top-level go.mod file.