guix-download: Error out when the HTTP response code is not 200.

* guix-download.in (http-fetch): Leave with an error message when
  RESPONSE's code is not 200.

* tests/guix-download.sh: New file.
* Makefile.am (TESTS): Add it.

build: Remove now unnecessary dependency of downloads on guix/utils.go.

* Makefile.am (distro/packages/bootstrap/x86_64-linux/guile-bootstrap-2.0.6.tar.xz,
  distro/packages/bootstrap/i686-linux/guile-bootstrap-2.0.6.tar.xz):
  Remove dependency on guix/utils.go.

distro: Move bootstrap tarball packages to (distro packages make-bootstrap).

* distro/packages/base.scm (binutils-final): Make public.
  (static-package, %bash-static, %static-inputs, %static-binaries,
  %binutils-static, %binutils-static-stripped, %glibc-stripped,
  %gcc-static, %gcc-stripped, %guile-static, %guile-static-stripped,
  tarball-package, %bootstrap-binaries-tarball,
  %binutils-bootstrap-tarball, %glibc-bootstrap-tarball,
  %guile-bootstrap-tarball): Move to...
* distro/packages/make-bootstrap.scm: ... here.  New file.
* Makefile.am (MODULES): Add it.

distro: Add GnuPG and companion libraries.

* distro/packages/gnupg.scm: New file.
* Makefile.am (MODULES): Add it.

distro: Add (distro packages compression).

* distro/packages/base.scm (gzip, bzip2, xz): Move to...
* distro/packages/compression.scm: ... here.  New file.
* Makefile.am (MODULES): Add it.

distro: Add GNU Pth.

* distro/packages/pth.scm: New file.
* Makefile.am (MODULES): Add it.

distro: Add GNU gperf.

* distro/packages/gperf.scm: New file.
* Makefile.am (MODULES): Add it.
* distro/packages/guile.scm (guile-reader): Use it.

distro: Split (distro packages base) into several files.

* distro/packages/base.scm (libsigsegv, gawk, perl, m4, gmp, mpfr, mpc,
  ncurses, readline, bash, libtool, libunistring, libffi, pkg-config,
  libgc): Move to modules of their own.
  (guile-1.8, guile-2.0): Move to...
* distro/packages/guile.scm: ... here.

* distro/packages/bash.scm, distro/packages/bdw-gc.scm,
  distro/packages/gawk.scm, distro/packages/libffi.scm,
  distro/packages/libsigsegv.scm, distro/packages/libtool.scm,
  distro/packages/libunistring.scm, distro/packages/m4.scm,
  distro/packages/multiprecision.scm, distro/packages/ncurses.scm,
  distro/packages/perl.scm, distro/packages/pkg-config.scm,
  distro/packages/readline.scm: New files.

distro: Move bootstrap packages to (distro packages bootstrap).

* distro/packages/base.scm (glibc-dynamic-linker, %bootstrap-guile,
  bootstrap-origin, package-from-tarball, %bootstrap-base-url,
  %bootstrap-coreutils&co, %bootstrap-binutils, %bootstrap-glibc,
  %bootstrap-gcc, %bootstrap-inputs, package-with-bootstrap-guile): Move
  to ...
* distro/packages/bootstrap.scm: ... here.  New file.
* Makefile.am (MODULES): Add it.
* tests/builders.scm: Use (distro packages bootstrap).
  (%bootstrap-guile): Remove.
* tests/packages.scm: Likewise.
* tests/union.scm: Likewise, and remove @@ to access %bootstrap-inputs.
* tests/derivations.scm: Use (distro packages bootstrap) and remove @@
  to access %bootstrap-coreutils&co.
* HACKING (When the platform is supported by Nixpkgs): Update
  accordingly.

distro: Go for one module per package.

The alternative, which was to use one module per category, would
probably not scale well.  First, because many packages could fall into
several categories (does GnuTLS go into "networking", "security", or
"libraries"?).  Second, because that could easily lead to circular
dependencies among modules ("security" and "networking" depend on each
other, etc.)

* distro/packages/databases.scm: Rename to...
* distro/packages/recutils.scm: ... this.
* distro/packages/typesetting.scm: Rename to...
* distro/packages/lout.scm: ... this.
* Makefile.am (MODULES): Adjust accordingly.
* po/POTFILES.in: Likewise.

Add (guix snix) and the `guix-import' command.

* guix/snix.scm, tests/snix.scm, guix-import.in: New files.
* configure.ac: Output `guix-import' and make it executable.
* Makefile.am (bin_SCRIPTS): Add `guix-import'.
  (MODULES): Add `guix/snix.scm'.
  (TESTS): Add `tests/snix.scm'.

build: Require GNU libgcrypt.

* guix/utils.scm (sha256): Remove Coreutils- and libchop-based
  implementations.
* README: Update accordingly.

* m4/guix.m4: New file.
* configure.ac: Use `GUIX_ASSERT_LIBGCRYPT_USABLE'.  Set and substitute
  `LIBGCRYPT_PREFIX'.
* Makefile.am (AM_DISTCHECK_CONFIGURE_FLAGS): Pass
  `--with-libgcrypt-prefix=$(LIBGCRYPT_PREFIX)'.

build: Produce (guix config) instead of using compile-time tricks.

* guix/config.scm.in: New file.
* guix/utils.scm: Use it.
  (%libgcrypt): Remove.
  (%nixpkgs-directory): Don't capture the compile-time $NIXPKGS; use
  %NIXPKGS instead.
  (nixpkgs-derivation): Use %NIX-INSTANTIATE.
* pre-inst-env.in (NIX_INSTANTIATE, NIXPKGS, LIBGCRYPT): Remove.

* configure.ac: Emit `guix/config.scm'.
* Makefile.am (GOBJECTS): Add `guix/config.go'.
  (nobase_nodist_guilemodule_DATA): Add `guix/config.scm'.

build: Clearly mark Nixpkgs as optional.

* configure.ac: Always show the result of checking for Nixpkgs.  Don't
  warn when Nixpkgs is not found.
* Makefile.am (AM_DISTCHECK_CONFIGURE_FLAGS): Remove `--with-nixpkgs'
  flag.
* guix/utils.scm (%nixpkgs-directory): Use either the compile-time or
  the run-time `NIXPKGS' environment variable.
* release.nix (jobs.tarball, jobs.build): Remove `--with-nixpkgs'
  configure flag.
* README: Mark Nixpkgs as optional.

* distro/packages/databases.scm, distro/packages/guile.scm,
  distro/packages/typesetting.scm: Change uses of `nixpkgs-derivation*'
  to `nixpkgs-derivation', to avoid failing at compile-time.

Add a preliminary `guix-package' command-line tool.

* guix-package.in, tests/guix-package.sh: New files.
* configure.ac: Output `guix-package'.
* Makefile.am (TESTS): Add `tests/guix-package.sh'.
  (bin_SCRIPTS): Add `guix-package'.

build: Add unit test for the `guix-build' command.

* tests/guix-build.sh: New file.
* Makefile.am (TESTS): Add it.
  (LOG_COMPILER): Rename to...
  (SCM_LOG_COMPILER): ... this.  Move flags to...
  (AM_SCM_LOG_FLAGS): ... this.
  (TEST_EXTENSIONS, SH_LOG_COMPILER, AM_SH_LOG_FLAGS): New variables.

Add (guix ui).

* guix/ui.scm: New file.
* Makefile.am (MODULES): Add it.
* po/POTFILES.in: Add it.

* guix-build.in: Use it.
  (_, N_, leave): Remove.
  (guix-build): Use `with-error-handling' instead of the `guard' form.
* guix-download.in: Use it.
  (_, N_, leave): Remove.

Add (guix build union).

* guix/build/union.scm, tests/union.scm: New files.
* Makefile.am (MODULES): Add `guix/build/union.scm'.
  (TESTS): Add `tests/union.scm'.

build: Preserve the executable bit of bootstrap binaries.

* Makefile.am (install-data-hook): New target.

build: Fix out-of-source-tree builds.

* Makefile.am (distro/packages/bootstrap/x86_64-linux/guile-bootstrap-2.0.6.tar.xz,
  distro/packages/bootstrap/i686-linux/guile-bootstrap-2.0.6.tar.xz):
  Make the target's parent directory.
* pre-inst-env.in (DISTRO_BOOTSTRAP_PATH): Add the builddir-relative
  directory.