daemon: Add `--listen'.

* nix/nix-daemon/guix-daemon.cc (GUIX_OPT_LISTEN): New macro.
  (options): Add `--listen'.
  (parse_opt): Handle it.
* doc/guix.texi (Invoking guix-daemon): Mention it.

daemon: Add `--listen'.

* nix/nix-daemon/guix-daemon.cc (GUIX_OPT_LISTEN): New macro.
  (options): Add `--listen'.
  (parse_opt): Handle it.
* doc/guix.texi (Invoking guix-daemon): Mention it.

Merge branch 'core-updates'

Conflicts:
	guix/build/union.scm

daemon: Fix warning message when running as root without a build user group.

* nix/nix-daemon/guix-daemon.cc (main): Fix warning message when running
  as root without `--build-users-group'.

guix-daemon: Rename `--build-cores' for consistency with `guix-build'.

* nix/nix-daemon/guix-daemon.cc (options): Change `--build-cores' to
  `--cores', and `-C' to `-c'.
  (parse_opt): Adjust accordingly.

Update a few more license headers.

* distro/packages/openssl.scm, m4/guix.m4, nix/sync-with-upstream:
  Update headers.

Merge branch 'master' into core-updates

Conflicts:
	build-aux/download.scm
	distro/packages/autotools.scm
	distro/packages/base.scm
	distro/packages/bootstrap.scm
	distro/packages/lsh.scm
	distro/packages/make-bootstrap.scm
	distro/packages/ncurses.scm
	distro/packages/perl.scm
	tests/derivations.scm
	tests/union.scm

Update license headers.

Change all license headers, except guix/build/* and ld-wrapper.scm, with
this code:

  (use-modules (guix build utils)
	       (srfi srfi-1))

  (fluid-set! %default-port-encoding "UTF-8")

  (substitute* (remove (lambda (f)
			 (or (string-contains f ".tar.")
			     (string-contains f ".git/")
			     (string-contains f ".so")
			     (string-suffix? ".o" f)
			     (string-suffix? ".a" f)
			     (string-suffix? ".go" f)
			     (string-suffix? ".pdf" f)
			     (string-suffix? ".png" f)
			     (string-suffix? ".info" f)
			     (equal? (basename f) "guix-daemon")
			     (equal? (basename f) "nix-setuid-helper")
			     (string-contains f "nix-upstream/")
			     (string-contains f "distro/packages/bootstrap/")))
		       (find-files "." "\\.[a-z]+$"))
    (("^([[:graph:]]+) This file is part of Guix." _ comment-start)
     (string-append comment-start " This file is part of GNU Guix."))
    (("^([[:graph:]]+) Guix --- Nix package management.*" _ comment-start)
     (string-append comment-start
		    " GNU Guix --- Functional package management for GNU\n"))
    (("^([[:graph:]]+) Guix is " _ comment-start)
     (string-append comment-start " GNU Guix is "))
    (("^([[:graph:]]+) along with Guix." _ comment-start)
     (string-append comment-start " along with GNU Guix."))
    (("^([[:graph:]]+) Copyright \\(C\\)" _ comment-start)
     (string-append comment-start " Copyright ©")))

Change headers using C-style comments manually.

daemon: Show the chroot contents upon `--debug'.

* nix/nix-daemon/guix-daemon.cc (main)[HAVE_CHROOT]: Display the
  contents of `settings.dirsInChroot' at `lvlDebug'.

daemon: Properly initialize libgcrypt.

* nix/nix-daemon/guix-daemon.cc (main): Call `gcry_check_version'.

daemon: Gracefully handle Nix errors.

* nix/nix-daemon/guix-daemon.cc (main): Run Nix code in an exception
  handler; gracefully print error messages, and exit with EXIT_FAILURE.

daemon: Warn against running as root without `--build-users-group'.

* nix/nix-daemon/guix-daemon.cc (main): Recommend using
  `--build-users-group' when running  as root without a build users
  group.

daemon: Add `--chroot-directory'.

* nix/nix-daemon/guix-daemon.cc (GUIX_OPT_CHROOT_DIR): New macro.
  (options): Add `--chroot-directory'.
  (parse_opt): Handle it.

Merge branch 'master' into core-updates

Conflicts:
	distro/packages/multiprecision.scm

daemon: Add `--debug' option.

* nix/nix-daemon/guix-daemon.cc (GUIX_OPT_DEBUG): New macro.
  (options): Add `--debug'.
  (parse_opt): Set `verbosity' upon GUIX_OPT_DEBUG.

daemon: Disable use of substitutes for now.

* nix/nix-daemon/guix-daemon.cc (main): Set `settings.useSubstitutes' to
  false, and `settings.substituters' to the empty list.

build: Avoid brace expansion in `nix/sync-with-upstream'.

* nix/sync-with-upstream: Avoid brace expansion, for the sake of Dash.

Merge branch 'nix-integration'

Conflicts:
	tests/guix-package.sh

daemon: Add more options.

* nix/nix-daemon/guix-daemon.cc (GUIX_OPT_BUILD_USERS_GROUP,
  GUIX_OPT_CACHE_FAILURES, GUIX_OPT_LOSE_LOGS,
  GUIX_OPT_DISABLE_STORE_OPTIMIZATION, GUIX_OPT_IMPERSONATE_LINUX_26):
  New macros.
  (options)["build-users-group", "cache-failures", "lose-logs",
  "disable-store-optimization", "impersonate-linux-2.6"]: New options.
  (parse_opt): Handle them.

daemon: Add `list-runtime-roots' script.

* nix/scripts/list-runtime-roots.in: New file.
* config-daemon.ac: Add `AC_CONFIG_FILES' invocation for it.
* daemon.am (nodist_pkglibexec_SCRIPTS): New variable.
  (AM_TESTS_ENVIRONMENT): Define `top_builddir'.
* tests/guix-daemon.sh: Export `NIX_ROOT_FINDER'.
* nix/sync-with-upstream: Substitute the path to the root finder in
  libstore/gc.cc.