guix-download: Add support for file:// URIs.

* guix-download.in (fetch-and-store): New procedure.
  (guix-download): Use it to compute PATH.  Call `add-to-store' when
  a `file' URI scheme is used.
* Makefile.am (AM_TESTS_ENVIRONMENT): New variable.
* tests/guix-download.sh: Add test.

guix-download: Gracefully handle invalid URIs.

* guix-download.in (guix-download): Error out when `string->uri'
  returns #f.  Use `leave' when the scheme is unknown.
* tests/guix-download.sh: Add tests.

distro: Add GNU Texinfo.

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

distro: Add GNU Libtasn1 and GnuTLS.

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

distro: Add GNU Nettle.

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

distro: Add LZO.

* distro/packages/compression.scm (lzo): New variable.

tests: Make sure to use the bootstrap Guile.

* tests/builders.scm ("url-fetch", "gnu-build"): Pass `url-fetch'
  #:guile %BOOTSTRAP-GUILE.

tests: Remove extraneous test.

* tests/derivations.scm ("build-expression->derivation for fixed-output
  derivation"): Remove test.  It is redundant with that in builders.scm,
  and doesn't work out of the box with the statically-linked
  %BOOTSTRAP-GUILE.

build: Add $(top_builddir) to the load path.

* Makefile.am (DOWNLOAD_FILE): Add $(top_builddir) to the search path,
  since that's where guix/config.scm is.
  (.scm.go): Likewise.

distro: Patch libc to avoid accessing /etc/ld.so.cache and friends.

* distro/packages/base.scm (glibc): Apply `glibc-no-ld-so-cache.patch'.
  (glibc-final): Inherit GLIBC's inputs.
* distro/packages/patches/glibc-no-ld-so-cache.patch: New file.
* Makefile.am (dist_patch_DATA): Add it.

distro: Use `mirror://' URLs.

* distro/packages/base.scm, distro/packages/bash.scm,
  distro/packages/compression.scm, distro/packages/gawk.scm,
  distro/packages/gperf.scm, distro/packages/guile.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/pth.scm, distro/packages/readline.scm,
  distro/packages/recutils.scm: Use `mirror://gnu' URLs.
* distro/packages/gnupg.scm: Use `mirror://gnupg' URLs.

download: Add support for mirror:// URLs.

* guix/download.scm (%mirrors): New variable.  Mirror lists taken from
  Nixpkgs.
  (url-fetch): New `mirrors' keyword parameter.
  [builder]: Pass it.

* guix/build/download.scm (url-fetch): New `mirrors' keyword parameter.
  [maybe-expand-mirrors]: New procedure.
  [uri]: Use it.

download: Follow HTTP redirections.

* guix/build/download.scm (http-fetch): Follow the redirection when CODE
  is 302.

Remove (guix http) and (guix ftp).

* guix/ftp.scm, guix/http.scm, guix/build/ftp.scm, guix/build/http.scm:
  Remove.
* Makefile.am (MODULES): Likewise.
* tests/builders.scm, distro/packages/base.scm,
  distro/packages/bash.scm, distro/packages/bdw-gc.scm,
  distro/packages/compression.scm, distro/packages/gawk.scm,
  distro/packages/gnupg.scm, distro/packages/gperf.scm,
  distro/packages/guile.scm, distro/packages/libffi.scm,
  distro/packages/libsigsegv.scm, distro/packages/libtool.scm,
  distro/packages/libunistring.scm, distro/packages/lout.scm,
  distro/packages/m4.scm, distro/packages/multiprecision.scm,
  distro/packages/ncurses.scm, distro/packages/perl.scm,
  distro/packages/pkg-config.scm, distro/packages/pth.scm,
  distro/packages/readline.scm, distro/packages/recutils.scm: Use
  `url-fetch' instead of `http-fetch' and `ftp-fetch'.
* distro/packages/bootstrap.scm: Likewise
  (bootstrap-origin): Remove references to `http-fetch' and
  `ftp-fetch'.
* guix.scm (%public-modules): Remove `http' and `ftp'; add `download'.

Add (guix download) and (guix build download).

* guix/download.scm, guix/build/download.scm: New files.
* Makefile.am (MODULES): Add them.
* tests/builders.scm ("url-fetch"): New test.
* distro/packages/bootstrap.scm (bootstrap-origin): Support
  `url-fetch'.
* guix/snix.scm (snix-derivation->guix-package): Use `url-fetch' instead
  of `http-fetch'.

Move base32 code to (guix base32).

* guix/utils.scm (bytevector-quintet-ref, bytevector-quintet-ref-right,
  bytevector-quintet-length, bytevector-quintet-fold,
  bytevector-quintet-fold-right, make-bytevector->base32-string,
  %nix-base32-chars, %rfc4648-base32-chars, bytevector->base32-string,
  bytevector->nix-base32-string, bytevector-quintet-set!,
  bytevector-quintet-set-right!, base32-string-unfold,
  base32-string-unfold-right, make-base32-string->bytevector,
  base32-string->bytevector, nix-base32-string->bytevector): Move to...
* guix/base32.scm: ... here.  New file.

* tests/utils.scm (%nix-hash, "bytevector->base32-string",
  "base32-string->bytevector", "nix-base32-string->bytevector", "sha256
  & bytevector->base32-string"): Move to...
* tests/base32.scm: ... here.  New file

* guix-download.in, guix/derivations.scm, guix/packages.scm,
  guix/snix.scm, tests/builders.scm, tests/derivations.scm: Adjust
  accordingly.
* guix.scm (%public-modules): Add `base32'.

tests: Choose a less expensive test for packages.

* tests/packages.scm (%bootstrap-inputs): Remove.
  ("GNU Hello"): Rename to...
  ("GNU Make, bootstrap"): ... this.  Build GNU-MAKE-BOOT0 instead of
  HELLO.

http: Add informative output.

* guix/build/http.scm (http-fetch): Emit message indicating the
  download.

http: Check the HTTP response code, and bail if not 200.

* guix/build/http.scm (http-fetch): Check RESP's code; error out when
  it's not 200.

derivations: build-expression->derivation: Builder only refers to sources.

* guix/derivations.scm (build-expression->derivation)[source-path]: New
  procedure.
  [builder]: Pass only sources as references.  This fixes a bug whereby
  changing a fixed-output drv referred to by a builder would cause the
  builder's hash to change, thereby leading to a full rebuild.
* tests/derivations.scm ("build-expression->derivation with a
  fixed-output input"): New test.