services: Add console-keymap service.

* gnu/services/base.scm (console-keymap-service): New procedure.
* doc/guix.texi (Base Services): Document it.

Co-authored-by: 宋文武 <iyzsong@gmail.com>

file-systems: Use a second 'mount' call for read-only bind mounts.

* gnu/build/file-systems.scm (MS_REMOUNT): New constant.
  (mount-file-system): Add 'flags' local variable.   When FLAGS has
  MS_BIND & MS_RDONLY, call 'mount' with MS_REMOUNT.
* gnu/services/base.scm (file-system-service) <start>: Likewise.

Merge branch 'master' into core-updates

doc: Add example showing how to customize 'nscd-service'.

* doc/guix.texi (Name Service Switch): Add link to nss-mdns.  Add
  example show how to pass #:name-services to 'nscd-service'.
  (Base Services): Add link from 'nscd-service' to the above.
* gnu/services/base.scm (nscd-service): Update docstring accordingly.

Merge branch 'master' into core-updates

services: syslog-service: Add 'config-file' argument.

* gnu/services/base.scm (syslog-service): Add 'config-file' keyword
argument.
* doc/guix.texi (Base Services): Document it.

Merge branch 'master' into core-updates

services: guix-service: Add service documentation.

* gnu/services/base.scm (guix-service): Add 'documentation' field to the
  service.

Merge branch 'master' into core-updates

services: guix-service: Add 'lsof' and 'lsh' to guix-daemon's $PATH.

* gnu/services/base.scm (guix-service): Add #:lsof and #:lsh parameters.
  [start]: Pass #:environment-variables to 'make-forkexec-constructor'.

Merge branch 'master' into core-updates

services: guix-service: Remove extraneous monadism.

* gnu/services/base.scm (guix-build-accounts): Remove unneeded
  'with-monad'.
  (guix-service): Adjust accordingly.

Merge branch 'master' into core-updates

services: nscd: Make sure /var/db/nscd exists.

* gnu/services/base.scm (nscd-service)[activate]: Make /var/db/nscd.

services: nscd-service: Add #:name-services parameter.

* gnu/services/base.scm (nscd-service): Add #:name-services parameter.
  In 'start' field, set LD_LIBRARY_PATH based on #:name-services.
* doc/guix.texi (Base Services): Document it.
  (Name Service Switch): Link to 'nscd-service'.

services: mingetty: Wait for udev.

* gnu/services/base.scm (mingetty-service): Add 'udev' to
  'requirement'.

services: guix: #:authorize-hydra-key? now defaults to #t.

* gnu/services/base.scm (guix-service): Change AUTHORIZE-HYDRA-KEY?
  default value to #t.

monads: Move '%store-monad' and related procedures where they belong.

This turns (guix monads) into a generic module for monads, and moves the
store monad and related monadic procedures in their corresponding
module.

* guix/monads.scm (store-return, store-bind, %store-monad, store-lift,
  text-file, interned-file, package-file, package->derivation,
  package->cross-derivation, origin->derivation, imported-modules,
  compiled, modules, built-derivations, run-with-store): Move to...
* guix/store.scm (store-return, store-bind, %store-monad, store-lift,
  text-file, interned-file): ... here.
  (%guile-for-build): New variable.
  (run-with-store): Moved from monads.scm.  Remove default value for
  #:guile-for-build.
* guix/packages.scm (default-guile): Export.
  (set-guile-for-build): New procedure.
  (package-file, package->derivation, package->cross-derivation,
  origin->derivation): Moved from monads.scm.
* guix/derivations.scm (%guile-for-build): Remove.
  (imported-modules): Rename to...
  (%imported-modules): ... this.
  (compiled-modules): Rename to...
  (%compiled-modules): ... this.
  (built-derivations, imported-modules, compiled-modules): New
  procedures.
* gnu/services/avahi.scm, gnu/services/base.scm, gnu/services/dbus.scm,
  gnu/services/dmd.scm, gnu/services/networking.scm,
  gnu/services/ssh.scm, gnu/services/xorg.scm, gnu/system/install.scm,
  gnu/system/linux-initrd.scm, gnu/system/shadow.scm, guix/download.scm,
  guix/gexp.scm, guix/git-download.scm, guix/profiles.scm,
  guix/svn-download.scm, tests/monads.scm: Adjust imports accordingly.
* guix/monad-repl.scm (default-guile-derivation): New procedure.
  (store-monad-language, run-in-store): Use it.
* build-aux/hydra/gnu-system.scm (qemu-jobs): Add explicit
  'set-guile-for-build' call.
* guix/scripts/archive.scm (derivation-from-expression): Likewise.
* guix/scripts/build.scm (options/resolve-packages): Likewise.
* guix/scripts/environment.scm (guix-environment): Likewise.
* guix/scripts/system.scm (guix-system): Likewise.
* doc/guix.texi (The Store Monad): Adjust module names accordingly.

services: user-processes: Really honor the grace delay.

* gnu/services/base.scm (user-processes-service): Change #:grace-delay
  default value to 4.  Define 'sleep*' and use it.

Merge branch 'master' into core-updates