Support Go 1.17 build stanzas (constraints)

[adamdecaf]

Go 1.17 is starting a migration with build constraints, so they are looking for //go:build ... stanzas in source files before any //+build ... lines. This breaks builds which check source code formatting/validation in CI that automatically updated.

It can be resolved with gofmt -s -w pkged.go which will add the required line. Example

The 1.17 release notes mention this change and the design proposal has a migration section for more details.

[adamdecaf]

FYI I know this project is being supplemented by go:embed so this issue could just serve as a quick fix for folks coming from Google searches.

[flamedmg]

Thank you Adam for this hint! Abandoned that lib and now feeling way better :)