distro: Add a bootstrap GCC tarball.

* distro/packages/base.scm (%gcc-stripped, %gcc-bootstrap-tarball): New
  variables.

distro: Add a bootstrap glibc tarball.

* distro/packages/base.scm (%glibc-stripped, %glibc-bootstrap-tarball):
  New variables.

distro: Add tools to build a tarball of statically-linked Binutils programs.

* distro/packages/base.scm (%binutils-static, %binutils-static-stripped,
  %binutils-bootstrap-tarball): New variables.

distro: Add a package to build a tarball of the bootstrap binaries.

* distro/packages/base.scm (tarball-package): New procedure.
  (%bootstrap-binaries-tarball): New variable.
  (%guile-bootstrap-tarball): Define in terms of `tarball-package'.

guix-build: Add `--system'.

* guix-build.in (derivations-from-package-expressions): New `system'
  parameter.  Pass it to `package-derivation'.
  (%default-options): Add `system' pair.
  (show-help): Describe `--system'.
  (%options): Add it.
  (guix-build): Check the `system' pair in OPTS; pass it to
  `derivations-from-package-expressions' and `package-derivation'.

distro: Provide a more descriptive report when a bootstrap binary is missing.

* distro/packages/base.scm (%bootstrap-guile): Error out when
  `search-bootstrap-binary' returns #f.

distro: Use the bootstrap Guile for the derivation of sources.

* distro/packages/base.scm (bootstrap-origin,
  package-with-bootstrap-guile): New procedures.
  (gnu-make-boot0, diffutils-boot0, findutils-boot0, binutils-boot0,
  gcc-boot0, linux-libre-headers-boot0, glibc-final, bash-final,
  guile-final): Use `package-with-bootstrap-guile'.
  (gcc-boot0-wrapped): Clear `source'.

* guix/ftp.scm (ftp-fetch): Add a #:guile keyword parameter.  Honor it.
* guix/http.scm (http-fetch): Likewise.

http/ftp: Tweak to avoid depending on libc's NSS.

* guix/build/http.scm (open-connection-for-uri): New procedure.
  (http-fetch): Use it.  Pass the result as a #:port argument to
  `http-get'.
  Add hack to modify the `set-port-encoding!' binding in (web response).

* guix/ftp-client.scm (ftp-open): Add optional `port' parameter,
  defaulting to 21.  When calling `getaddrinfo', convert PORT to a
  string and pass AI_NUMERICSERV when PORT is a number.

guix-build: Add `--local-build'.

* guix-build.in (show-help): Add `--local-build'.
  (%options): Likewise.
  (guix-build): Pass `set-build-options' the #:use-substitutes? argument
  accordingly.

distro: bzip2: Simplify installation phase with `find-files'.

* distro/packages/base.scm (bzip2): Use `find-files' instead of rolling
  our own with `file-system-fold'.

distro: %static-binaries: Use (guix build utils).

* distro/packages/base.scm (%static-binaries): Add missing
  use of (guix build utils).

distro: Fix bootstrapping regression recently introduced.

* distro/packages/base.scm (gcc-boot0-wrapped): Fix typo introduced in
  a52e429f76282080c58444ce2ac82a1968d5f29d ("distro: Add i686 support.")

distro: Clear references to the store in static binaries.

* distro/packages/base.scm (%static-binaries): Clear references to the
  store path for files in $out/bin.

utils: Add `find-files'.

* guix/build/utils.scm (find-files): New procedure.

utils: Add `copy-recursively'; use it.

* guix/build/utils.scm (copy-recursively): New procedure.

* distro/packages/base.scm (%guile-static-stripped): Use it.

utils: Add `mkdir-p'; use it.

* guix/build/utils.scm (mkdir-p): New procedure.

* distro/packages/base.scm (gnu-make-boot0, gcc-boot0-wrapped,
  ld-wrapper-boot3, %static-binaries, %guile-static-stripped): Use it.
* distro/packages/typesetting.scm (lout): Likewise.

build-system/gnu: Pass the system type to the builder.

* guix/build-system/gnu.scm (gnu-build)[builder]: Pass SYSTEM to
  `gnu-build' as a keyword argument.

distro: Add i686 support.

* distro/packages/base.scm (gcc-4.7): Turn `arguments' into a lambda.
  Use `glibc-dynamic-linker' instead of the hard-coded linker name.

distro: Switch to Linux-Libre.

* distro/packages/base.scm (linux-headers): Rename to...
  (linux-libre-headers): ... this.  Change `name', `source', and
  `description', and `home-page' accordingly.  Update users.
  (linux-headers-boot0): Rename to...
  (linux-libre-headers-boot0): ... this.  Update users.

distro: Use our own pre-built Guile to bootstrap.

* distro/packages/base.scm (%bootstrap-guile): Build from a tarball
  containing a pre-built Guile.

* distro.scm (%bootstrap-binaries-directory): New variable.
  (search-bootstrap-binary): New procedure.

* Makefile.am (bootstrapdir, bootstrap_x86_64_linuxdir,
  dist_bootstrap_x86_64_linux_DATA, DISTCLEANFILES, DOWNLOAD_FILE): New
  variables.
  (distro/packages/bootstrap/x86_64-linux/guile-bootstrap-2.0.6.tar.xz):
  New rule.
  (EXTRA_DIST): Add `build-aux/download.scm'.
  (.scm.go): Define the `DISTRO_BOOTSTRAP_DIRECTORY' and
  `DISTRO_INSTALLED_BOOTSTRAP_DIRECTORY' environment variables.

* pre-inst-env.in: Define `DISTRO_BOOTSTRAP_DIRECTORY'.

* build-aux/download.scm: New file.
* distro/packages/bootstrap/x86_64-linux/{bash, mkdir, tar, xz}: New
  files.