distro: gcc: No longer store the absolute path of crt files.

* distro/packages/base.scm (gcc-4.7): Define
  STANDARD_STARTFILE_PREFIX_[12] instead of storing the absolute path of
  crt files.

distro: Fix GCC tarball to include the `libexec' directory.

* distro/packages/base.scm (%gcc-stripped): Copy $gcc/libexec to $out.

distro: Fix glibc tarball to include *.so.*.

* distro/packages/base.scm (%glibc-stripped): Fix regexp to
  include *.so.* in the output.

distro: Add a statically-linked GCC for bootstrapping.

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

distro: Add a package that gets the bootstrap glibc from a tarball.

* distro/packages/base.scm (%bootstrap-glibc): New variable.

distro: Add packages that get Coreutils, Binutils & co. from tarballs.

* distro/packages/base.scm (package-from-tarball): New procedure.
  (%bootstrap-base-url, %bootstrap-coreutils&co, %bootstrap-binutils):
  New variables.

packages: Add support for system-dependent inputs.

* guix/packages.scm (package-derivation)[intern]: New procedure.  Pass
  #t as the `recursive?' argument, instead of #f.
  [expand-input]: New procedure, with code formerly in the body.
  Support inputs where the input is a procedure returning a file name or
  an <origin>.
  Use `expand-input' in the body.

* tests/packages.scm ("trivial with system-dependent input"): New test.

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.