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.

distro: Use (guix licenses) instead of strings.

* distro/packages/acl.scm, distro/packages/attr.scm,
  distro/packages/autotools.scm, distro/packages/base.scm,
  distro/packages/bash.scm, distro/packages/bdw-gc.scm,
  distro/packages/bison.scm, distro/packages/bootstrap.scm,
  distro/packages/compression.scm, distro/packages/cpio.scm,
  distro/packages/ddrescue.scm, distro/packages/ed.scm,
  distro/packages/flex.scm, distro/packages/gawk.scm,
  distro/packages/gdbm.scm, distro/packages/gettext.scm,
  distro/packages/gnupg.scm, distro/packages/gnutls.scm,
  distro/packages/gperf.scm, distro/packages/guile.scm,
  distro/packages/help2man.scm, distro/packages/less.scm,
  distro/packages/libffi.scm, distro/packages/libsigsegv.scm,
  distro/packages/libunistring.scm, distro/packages/linux.scm,
  distro/packages/lout.scm, distro/packages/lsh.scm,
  distro/packages/m4.scm, distro/packages/multiprecision.scm,
  distro/packages/nano.scm, distro/packages/ncurses.scm,
  distro/packages/nettle.scm, distro/packages/perl.scm,
  distro/packages/pkg-config.scm, distro/packages/pth.scm,
  distro/packages/readline.scm, distro/packages/recutils.scm,
  distro/packages/shishi.scm, distro/packages/system.scm,
  distro/packages/texinfo.scm, distro/packages/time.scm,
  distro/packages/wget.scm, distro/packages/which.scm,
  distro/packages/zile.scm: Use (guix licenses).

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

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

daemon: Build `nix-setuid-helper'.

* daemon.am (libexec_PROGRAMS, nix_setuid_helper_SOURCES,
  nix_setuid_helper_CPPFLAGS, nix_setuid_helper_LDADD): New variables.
* test-env.in: Set and export `NIX_SETUID_HELPER'.
* README (Installing Guix as non-root): New section.

download: Work around (web client) bug <http://bugs.gnu.org/13095>.

* guix/build/download.scm: Annihilate `shutdown' in (web client).

release.nix: Remove trailing "/nix" from localstatedir.

* release.nix (tarball, build): Use /nix/var as localstatedir, as a
  follow-up to 7f4f065.

build: Fix default value of `%state-directory'.

* guix/config.scm.in (%state-directory): Append `/nix'.
  Reported by Andreas Enge <andreas@enge.fr>.

build: Have `bootstrap' run all the necessary steps.

* bootstrap: Always run "git submodule init".  Run
  `nix/sync-with-upstream'.
  Reported by Nikita Karetnikov and Andreas Enge.

guix-package: Avoid use of the `guix' sub-directory for profiles.

* guix-package.in (%current-profile): Change to `guix-profile'.

release.nix: tarball: Fix typo.

* release.nix (tarball): Replace "gnulib" by "nix".

guix-package: Use directory names from (guix config).

* guix-package.in (%profile-directory): Use %STATE-DIRECTORY instead of
  a hard-coded directory.

distro: lout: Comment out dependency on Ghostscript.

* distro/packages/lout.scm (lout): Temporarily comment out dependency on
  Ghostscript as this was causing evaluation errors on Hydra.

Merge branch 'nix-integration'

Conflicts:
	tests/guix-package.sh

release.nix: Add `build_disable_daemon'.

* release.nix (build_disable_daemon): New job.

release.nix: build: Allow builds within a chroot.

* release.nix (build): Remove `__noChroot' and `preConfigure'.

tests: Skip network-dependent tests when the network is unreachable.

* tests/builders.scm (network-reachable?): New variable.
  ("url-fetch", "gnu-build"): Skip unless NETWORK-REACHABLE?.
* tests/derivations.scm (%coreutils): Check for network access.
  ("build-expression->derivation with one input"): Skip when %COREUTILS
  is #f.
* tests/guix-package.sh: Skip installation of GNU Make when the network
  is unreachable.
* tests/packages.scm ("GNU Make, bootstrap"): Likewise.
* tests/union.scm ("union-build"): Likewise.

release.nix: Build the daemon.

* release.nix (tarball): Add `preAutoconf'.  Augment `buildInputs' and
  `configureFlags' to allow daemon builds.
  (build): Likewise.

build: Make `--enable-daemon' the default.

* configure.ac: Have $guix_build_daemon default to "yes".

build: When `--enable-daemon', don't error out when Nix programs are missing.

* config-daemon.ac: Move AC_ARG_ENABLE([daemon]...)...
* configure.ac: ... here.
  When Nix programs are not found, error out only when
  $guix_build_daemon is no.