build-system/python: 'package-with-python2' preserves source location.

* guix/build-system/python.scm (package-with-explicit-python): Add
  'location' field.

guix: Add a "pypi-uri" helper method.

* guix/download.scm (mirrors): New "pypi" mirror.
* guix/build-system/python.scm (pypi-uri): New method.

Merge branch 'master' into dbus-update

build-system/gnu: dist-package: Use 'autoconf-wrapper'.

* guix/build-system/gnu.scm (dist-package): Use AUTOCONF-WRAPPER instead
  of AUTOCONF.

build-system/python: Memoize the results of 'package-with-python2'.

Fixes <http://bugs.gnu.org/21675>.
Reported by Cyril Roelandt <tipecaml@gmail.com>.

Before this change, the command:

  guix build python2-oslo.utils -n --no-substitutes

would take 17.5s.  After, it is down to 2.9s.
Likewise, the command:

  guix graph python2-bandit | grep python2-setuptools.*Helve| wc -l

would return 412 nodes before, all functionally equivalent, and returns
a single one now.

* guix/build-system/python.scm (package-with-explicit-python): Remove
  'p' parameter.  Change to return a one-argument memoizing procedure.
  (package-with-python2): Adjust accordingly.

Merge branch 'core-updates'

Use "normalized codesets" everywhere.

In other words, change "xx_YY.UTF-8" to "xx_YY.utf8".

* guix/profiles.scm (ca-certificate-bundle): Use "en_US.utf8" instead of
  "en_US.UTF-8".
* guix/packages.scm (patch-and-repack): Likewise.
* guix/build/gnu-build-system.scm (install-locale): Likewise.
* guix/build-system/gnu.scm (gnu-build, gnu-cross-build): Likewise.
* gnu/packages/python.scm (python-ipython): Likewise.
* gnu/packages/gawk.scm (gawk): Likewise.
* build-aux/hydra/demo-os.scm: Likewise.
* gnu/packages/guile.scm (guile-ncurses)[arguments]: Remove
  'change-locale' phase.

Merge branch 'core-updates'

Merge branch 'master' into core-updates

build: Add cran-uri procedure.

* guix/build-system/r.scm (cran-uri): New procedure.

Merge branch 'master' into core-updates

build-system/glib-or-gtk: Don't generate 'icon-theme.cache'.

* guix/build-system/glib-or-gtk.scm (default-gtk+): Remove.
  (lower): Adjust accordingly.
* guix/build/glib-or-gtk-build-system.scm (generate-icon-cache): Remove.
  (%standard-phases): Remove 'glib-or-gtk-icon-cache' phase.

build: Add R build system.

* guix/build-system/r.scm: New file.
* guix/build/r-build-system: New file.
* Makefile.am (MODULES): Add new files.
* doc/guix.texi (Build Systems): Document r-build-system.

build: ruby: Rewrite build system to use gem archives.

Co-Authored-By: Pjotr Prins <pjotr.public01@thebird.nl>

* guix/build-system/ruby.scm (lower): Remove git dependency.
  (rubygems-uri): New procedure.
* guix/build/ruby-build-system (gitify): Delete.
  (unpack): Use 'gem unpack' utility.
  (check): Add docstring.
  (build): Repack modified gem.
  (install): Rebuild unpacked gem and install it.
  (%standard-phases): Remove gitify and build phases.
* gnu/packages/ruby.scm (ruby-hoe, ruby-rake-compiler, ruby-i18n,
  ruby-rspec-support, ruby-rspec-core, ruby-diff-lcs-for-rspec,
  ruby-rspec-expectations, ruby-rspec-mocks, ruby-rspec, bundler,
  ruby-useragent, ruby-bacon, ruby-arel, ruby-connection-pool,
  ruby-net-http-persistent, ruby-minitest, ruby-minitest-sprint,
  ruby-minitest-bacon, ruby-daemons, ruby-git, ruby-slop,
  ruby-multipart-post): Convert to new build system.
* doc/guix.texi (ruby-build-system): Document the gem archive requirement.

Merge branch 'core-updates'

Merge branch 'master' into core-updates

build-system/ruby: Add #:gem-flags parameter.

* guix/build-system/ruby.scm (build): add 'gem-flags' key
* guix/build/ruby-build-system.scm (build): use 'gem-flags' key
* doc/guix.texi (Build Systems): Mention #:gem-flags.

Co-authored-by: Ludovic Courtès <ludo@gnu.org>

build-system/gnu: Pass --build=<triplet> to configure by default.

* guix/build-system/gnu.scm (gnu-build, gnu-cross-build): Accept #:build
  keyword argument.  Pass it to 'gnu-build' on the build side.
* guix/build/gnu-build-system.scm (configure): Accept #:build keyword
  argument.  Unless it is false, pass --build to configure.

build: Add 'emacs-build-system'.

* Makefile.am (MODULES): Add 'guix/build-system/emacs.scm' and
  'guix/build/emacs-build-system.scm'.
* guix/build-system/emacs.scm: New file.
* guix/build/emacs-build-system.scm: New file.
* doc/guix.texi (Build Systems): Document it.

derivations: Add #:substitutable?, distinguished from #:local-build?.

Fixes <http://bugs.gnu.org/18747>.

* guix/derivations.scm (substitutable-derivation?): Rewrite to check for
  "allowSubstitutes".
  (derivation): Add #:substitutable? parameter.
  [user+system-env-vars]: Honor it.
  (build-expression->derivation): Add #:substitutable? and honor it.
* guix/gexp.scm (gexp->derivation): Likewise.
* tests/derivations.scm ("derivation-prerequisites-to-build and substitutes,
  non-substitutable build"): Use #:substitutable? instead of #:local-build?.
  ("substitutable-derivation?", "derivation-prerequisites-to-build and
  substitutes, local build"): New tests.
* guix/download.scm (url-fetch): Adjust comment.
* guix/git-download.scm (git-fetch): Likewise.
* guix/build-system/gnu.scm (gnu-build, gnu-cross-build): Use #:substitutable?
  instead of #:local-build?.
* doc/guix.texi (Derivations, G-Expressions): Adjust accordingly.