Add `guix-download'.

* guix-download.in: New file.
* configure.ac: Emit `guix-download' and make it executable.
* Makefile.am (bin_SCRIPTS): Add `guix-download'.
* po/POTFILES.in: Add `guix-download.in'.

store: Add `query-path-hash'.

* guix/store.scm (write-arg, read-arg): Add `base16' literal and
  corresponding rule.
  (query-path-hash): New operation.

* tests/derivations.scm ("fixed-output derivation"): Check whether
  `query-path-hash' returns a bytevector.

distro: Add missing commands in the bootstrap binaries.

* distro/packages/base.scm (%static-inputs): Add an `awk' -> `gawk', and
  `sh' -> `bash' symlinks.  Add `fgrep' and `egrep'.
  (%bootstrap-coreutils&co): Use new tarball that contains that
  symlink.

* distro/packages/bootstrap/x86_64-linux/bash,
  distro/packages/bootstrap/x86_64-linux/mkdir,
  distro/packages/bootstrap/x86_64-linux/tar,
  distro/packages/bootstrap/x86_64-linux/xz: Use binaries from that
  tarball (the previous binaries hadn't gone through
  `remove-store-references', which is fixed now.)

guix-build: Change `--local-build' to `--no-substitutes'.

* guix-build.in (%default-options): Add `substitutes?'.
  (show-help): Change `--local-build' to `--no-substitutes'.
  (guix-build): Adjust accordingly.

distro: Update file name of initial Binutils tarball.

* distro/packages/base.scm (%bootstrap-binutils): Update remote file
  name.

derivations: Compile the #:modules passed to `build-expression->derivation'.

* guix/derivations.scm (imported-files)[parent-dirs]: Move to...
  (parent-directories): ... here.  New procedure.
  (compiled-modules): New procedure.
  (build-expression->derivation): Use it.

* tests/derivations.scm ("build-expression->derivation with modules"):
  New test.

distro: Update bootstrap glibc package.

* distro/packages/base.scm (%bootstrap-glibc): Update initial regexp to
  make it less Nixish.  Update hash to new tarball.

distro: Add required Linux-Libre headers to the glibc tarball.

* distro/packages/base.scm (%glibc-stripped): Include required headers
  from Linux-Libre.

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'.