lang/go: Add bsd.go.mk and use it for go124 and go125

Previously, we used lang/go-devel as a MASTERDIR, but go-devel itself
was really old (essentially 3 years old), and Go doesn't have the
concept of a public "development" version anymore.

Rather than tying modern Go ports to a vestigial version that nobody
should actually use, this commit adds a bsd.go.mk that Go ports can
include. This allows us to get lang/go* Makefiles down to 3 lines.

While here, extend the pkg-descr for both lang/go and the lang/go1*
ports to help users understand what's installing what.

This "new" framework (gently modified from go-devel/Makefile, so all
credit goes to everyone involved in creating that file) provides for
a default pkg-descr, but keeps each port responsible for its own
patches.

No functional changes are intended other than a slightly extended
pkg-descr (not even important enough to bump PORTREVISIONs here). Any
change in behaviour is a bug.

lang/go125: Update to 1.25.6

Changes:
  go1.25.6 (released 2026-01-15) includes security fixes to the go
  command, and the archive/zip, crypto/tls, and net/url packages, as well
  as bug fixes to the compiler, the runtime, and the crypto/tls, errors,
  and os packages.

lang/go125: Update to 1.25.5

Changes: go1.25.5 (released 2025-12-02) includes two security fixes to
         the crypto/x509 package, as well as bug fixes to the mime and os
         packages. See the Go 1.25.5 milestone on our issue tracker for
	 details.

lang/go125: Update to 1.25.4

Changes: go1.25.4 (released 2025-11-05) includes fixes to the compiler,
  the runtime, and the crypto/subtle, encoding/pem, net/url, and os
  packages.

lang/go-devel: move portscout to master port

Implements PORTSCOUT for all lang/go1* ports.

PR:	290231
Fixes:	c6297af4eff5e120d01d0c86c2d25d49418f389e "lang/go12[45]: silence
portscout"

lang/go12[45]: silence portscout

Because this does not make sense:

Port                                            | Current version | New version
------------------------------------------------+-----------------+------------
lang/go124                                      | 1.24.8          | 1.25.3
------------------------------------------------+-----------------+------------

And pet portclippy in the meantime by reordering some variables.

lang/go125: Update to 1.25.3.

Changes: go1.25.3 (released 2025-10-13) includes fixes to the
crypto/x509 package. See the Go 1.25.3 milestone on our issue tracker
for details.

lang/go125: Update to 1.25.2

Changes:

  go1.25.2 (released 2025-10-07) includes security fixes to the
  archive/tar, crypto/tls, crypto/x509, encoding/asn1, encoding/pem,
  net/http, net/mail, net/textproto, and net/url packages, as well as bug
  fixes to the compiler, the runtime, and the context, debug/pe, net/http,
  os, and sync/atomic packages. See the Go 1.25.2 milestone on our issue
  tracker for details.

lang/go125: Update to 1.25.1

Changes: go1.25.1 (released 2025-09-03) includes security fixes to the
net/http package, as well as bug fixes to the go command, and the net,
os, os/exec, and testing/synctest packages.

lang/go125: Add port

Introduction to Go 1.25¶

The latest Go release, version 1.25, arrives in August 2025, six months
after Go 1.24. Most of its changes are in the implementation of the
toolchain, runtime, and libraries. As always, the release maintains the
Go 1 promise of compatibility. We expect almost all Go programs to
continue to compile and run as before.

https://go.dev/doc/go1.25