regexp/syntax: cleanup code generation in perl_groups.go
Cleanup code generation of perl_groups.go:
* Fix the generated code header to follow the standard https://go.dev/s/generatedcode
* Apply gofmt as last step of code generation
* Add //go:generate lines in parse.go to trigger code generation
* Adapt make_perl_groups.pl to handle writing directly to the output
file (as we can't use shell redirection in go:generate lines)
* use strict; use warnings;
Change-Id: I675241da03dd3f6facc9eb9de00999bd9203ad70
Reviewed-on: https://go-review.googlesource.com/c/go/+/555995 Reviewed-by: Bryan Mills <bcmills@google.com> Reviewed-by: Dmitri Shuralyov <dmitshur@google.com> Reviewed-by: Ian Lance Taylor <iant@google.com>
Auto-Submit: Ian Lance Taylor <iant@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>