etc: Move manifests to a separate directory.

* etc/disarchive-manifest.scm, etc/hurd-manifest.scm,
etc/kernels-manifest.scm, etc/release-manifest.scm,
etc/source-manifest.scm, etc/system-tests.scm,
etc/time-travel-manifest.scm, etc/upgrade-manifest.scm: Move to…
* etc/manifests: … here, and drop “-manifest” from file name.
* Makefile.am (EXTRA_DIST, assert-binaries-available, check-system):
Adjust accordingly.

Change-Id: Iedee3d0cdd42e72ef8bbf654ea5d3b47dca95874

etc/manifests/kernels.scm

@@ -0,0 +1,35 @@
+;;; GNU Guix --- Functional package management for GNU
+;;; Copyright © 2022 Leo Famulari <leo@famulari.name>
+;;;
+;;; This file is part of GNU Guix.
+;;;
+;;; GNU Guix is free software; you can redistribute it and/or modify it
+;;; under the terms of the GNU General Public License as published by
+;;; the Free Software Foundation; either version 3 of the License, or (at
+;;; your option) any later version.
+;;;
+;;; GNU Guix is distributed in the hope that it will be useful, but
+;;; WITHOUT ANY WARRANTY; without even the implied warranty of
+;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+;;; GNU General Public License for more details.
+;;;
+;;; You should have received a copy of the GNU General Public License
+;;; along with GNU Guix.  If not, see <http://www.gnu.org/licenses/>.
+
+;;; This file returns a manifest of packages related to linux-libre.
+;;; Simplistically, it selects packages whose names begin with "linux-libre".
+;;; It is used to assist continuous integration of the kernel packages.
+
+(use-modules (guix packages)
+             (guix profiles)
+             (gnu packages))
+
+(manifest
+  (map package->manifest-entry
+       (fold-packages
+         (lambda (package lst)
+           (if (string-prefix? "linux-libre"
+                               (package-name package))
+             (cons package lst)
+             lst))
+         '())))