gnu: linux-libre@4.9: Update to 4.9.225.

* gnu/packages/linux.scm (linux-libre-4.9-version): Update to 4.9.225.
(linux-libre-4.9-pristine-source): Update hash.

gnu: linux-libre@4.4: Update to 4.4.225.

* gnu/packages/linux.scm (linux-libre-4.4-version): Update to 4.4.225.
(linux-libre-4.4-pristine-source): Update hash.

doc: Use existing URLs and file names in installation instructions.

Some users are confused that these URLs and file names don't work, so
change them to the most popular architecture, while still mentioning
alternatives.

* doc/guix.texi (USB Stick and DVD Installation, Binary Installation): Use
x86_64-linux URLs by default.

gnu: jucipp: Update to 1.6.0.

* gnu/packages/text-editors.scm (jucipp): Update to 1.6.0.
[arguments]: Remove obsolete phase.
[inputs]: Add UNIVERSAL-CTAGS.

gnu: Add Universal Ctags.

* gnu/packages/code.scm (universal-ctags): New public variable.

gnu: Add packcc.

* gnu/packages/c.scm (packcc): New public variable.

gnu: code.scm: Sort module imports.

* gnu/packages/code.scm (define-module): Sort imports.

gnu: Add facter.

* gnu/packages/admin.scm (facter): New public variable.

gnu: ruby-thor: Update to 1.0.1.

* gnu/packages/ruby.scm (ruby-thor): Update to 1.0.1.
[source]: Switch to GIT-FETCH.
[arguments]: Remove #:tests?.  Add #:phases.
[native-inputs]: Remove BUNDLER.  Add RUBY-RSPEC and RUBY-SIMPLECOV.

gnu: Add ruby-sys-filesystem.

* gnu/packages/ruby.scm (ruby-sys-filesystem): New public variable.

gnu: Add ruby-mkmf-lite.

* gnu/packages/ruby.scm (ruby-mkmf-lite): New public variable.

gnu: Add ruby-ptools.

* gnu/packages/ruby.scm (ruby-ptools): New public variable.

gnu: hdf4: Provide an absolute reference to libjpeg.

* gnu/packages/maths.scm (hdf4)[arguments]: Add phase
'provide-absolute-libjpeg-reference'.

Revert some Go package updates.

This reverts commit 5f833e0495f00a72f8d34a63e8afbc531afdd22d through
681ac9a66c26d2c739e41f03228f8c63fc0df482.

It's not idiomatic to update Go packages independently of their users.
This reversion was approved by Efraim on #guix:

http://logs.guix.gnu.org/guix/2020-05-26.log

* gnu/packages/golang.scm,
gnu/packages/syncthing.scm,
gnu/packages/tls.scm: Revert.

gnu: emacs-forge: Update to commit 09bf8ad.

* gnu/packages/emacs-xyz.scm (emacs-forge): Update to 09bf8ad.
[native-inputs]: Remove emacs-minimal, which is implicitly provided by the
emacs-build-system.

gnu: emacs-transient: Update to commit a6e4cced.

This is necessary to build a recent version of emacs-forge.

* gnu/packages/emacs-xyz.scm (emacs-transient): Update to commit a6e4cced.
[build-system]: Switch to the emacs-build-system.
[arguments]: Remove the #:modules, #:imported-modules and #:make-flags
arguments.
[phases]{configure}: Do not delete.
{install}: Do not replace.
{build-info-manual}: New phase.
{enter-lisp-directory}: New phase.
[native-inputs]: Remove emacs-minimal, which is implicitly provided by the
emacs-build-system.

gnu: emacs-evil-magit: Update to commit 253c644.

This resolves tests failures that appeared with the update to emacs-magit.

* gnu/packages/emacs-xyz.scm (emacs-evil-magit): Update to commit 253c644.

gnu: emacs-magit: Update to commit d05545e.

* gnu/packages/emacs-xyz.scm (emacs-magit): Update to commit
68b5a13fa1b6b122d4a2547b8c415aadff83d8ca.
[origin]: Remove obsoleted patches and snippets.
[build-system]: Switch to the emacs-build-system.
[arguments]: Remove the #:modules and #:imported-modules arguments.  Enable
tests. Remove the #:make-flags and #:test-target argument.  Specify the
\#:test-command argument.
[phases]{patch}: Remove phase.
{build-info-manual, set-magit-version, configure-git}
{disable-tramp-test}: New phases.
{configure}: Do not delete phase.
{patch-exec-paths}: Adapt file names.
* gnu/packages/patches/emacs-magit-log-format-author-margin.patch: Remove file.
* gnu/local.mk (dist_patch_DATA): Unregister it.

gnu: Add emacs-libgit.

* gnu/packages/emacs-xyz.scm (emacs-libgit): New variable.
* gnu/packages/patches/emacs-libgit-use-system-libgit2.patch: New file.
* gnu/local.mk (dist_patch_DATA): Register patch.

gnu: Add guile-rdf.

* gnu/packages/guile-xyz.scm (guile-rdf): New variable.