hydra: Really disable 32-to-64-bit cross-builds.

Fixes <http://bugs.gnu.org/26022>.
Reported by Efraim Flashner <efraim@flashner.co.il>.

* build-aux/hydra/gnu-system.scm (hydra-jobs)[cross-jobs](from-32-to-64?):
Check whether TARGET contains "64" rather than checking whether TARGET
ends in "64", which is rarely the case.
(same?): Add special case for armhf-linux.

gexp: Expose functions to allow creating derivation builders.

* guix/gexp.scm: Add load-path-expression and gexp-modules to the public
  interface of the module.  See <http://bugs.gnu.org/26023>.

gnu: Add rsnapshot.

* gnu/packages/backup.scm (rsnapshot): New variable.

gnu: python-fake-factory: Add back missing patch file.

This reverts the removal of "python-fake-factory-fix-build-32bit.patch"
by commit ce7911ddae5d30ba73c8c9552b7d4e71268e5db3.

* gnu/packages/patches/python-fake-factory-fix-build-32bit.patch: New file.
* gnu/local.mk (dist_patch_DATA): Add it.

gnu: inetutils: Set the $localstatedir.

This is a followup to commit 6f5d28f9d05aaa9743b3aac6bceb2c6323122d2d.

* gnu/packages/admin.scm (inetutils)[arguments]: Pass
'--localstatedir=/var' to #:configure-flags.

gnu: icecat: Add fixes from upstream Firefox ESR 45.8.0.

Includes fixes for CVE-2017-5398, CVE-2017-5400, CVE-2017-5401, CVE-2017-5402,
CVE-2017-5404, CVE-2017-5405, CVE-2017-5407, CVE-2017-5408, CVE-2017-5409, and
CVE-2017-5410.

* gnu/packages/gnuzilla.scm (icecat)[source]: Add selected fixes from the
upstream mozilla-esr45 repository.

gnu: icecat: Update to 45.7.0-gnu1.

* gnu/packages/gnuzilla.scm (icecat): Update to 45.7.0-gnu1.  Remove patches
included in 45.7.0.

utils: Use an idiom compatible with both 2.0 and 2.2.

Fixes a regression introduced in 7447aa36e16fb77f75df4d3369db9c942615632e.
Reported by Ricardo Wurmus.

* guix/utils.scm: Revert 7447aa36e16fb77f75df4d3369db9c942615632e.  Use
  #:prefix for (ice-9 iconv) to support both 2.0 and 2.2.

gnu: r: Remove obsolete configure flags.

* gnu/packages/statistics.scm (r)[arguments]: Remove obsolete configure flags.

gnu: r: Update to 3.3.3.

* gnu/packages/statistics.scm (r): Update to 3.3.3.

gnu: Add lensfun.

* gnu/packages/photo.scm (lensfun): New variable.

utils: Make sure to use the right 'bytevector->string'.

In Guile 2.2, (rnrs io ports) exports 'bytevector->string', which
conflicts with that of (ice-9 iconv).

* guix/utils.scm: Hide 'bytevector->string' from (rnrs io ports).

packages: Use PACKAGE@VERSION syntax when reporting ambiguities.

* gnu/packages.scm (%find-package): Upon ambiguity, use the
PACKAGE@VERSION syntax instead of 'package-full-name'.

list-runtime-roots: Bufferize the lsof pipe.

* nix/scripts/list-runtime-roots.in (lsof-roots): Add 'setvbuf' call for
PIPE.

ui: Don't use '%default-port-encoding' to set the encoding of string ports.

* guix/ui.scm (right-arrow): Call 'set-port-encoding!' to set PORT's
encoding; remove use of 'with-fluids'.  This is for compatibility with
Guile 2.2 where the encoding of string ports is not influenced by
%DEFAULT-PORT-ENCODING.
* tests/ui.scm ("show-manifest-transaction"): Likewise.

ui: Avoid '_' as a pattern variable in 'match'.

* guix/ui.scm (fill-paragraph): Don't use '_' as a pattern variable
since that is shadowed by the top-level '_' binding on Guile 2.2.
(show-manifest-transaction): Likewise.

download: Update the Savannah mirror list.

* guix/download.scm (%mirrors) <savannah>: Remove centervenus.com, which
seems to be broken.  Add download-mirror.sv.gnu.org as a last resort.

gnu: Add guile2.2-haunt.

* gnu/packages/guile.scm (guile2.2-haunt): New variable.

gnu: Add guile2.2-reader.

* gnu/packages/guile.scm (guile2.2-reader): New variable.

gnu: guile-reader: Update to 0.6.2.

* gnu/packages/guile.scm (guile-reader): Update to 0.6.2.
[arguments]: Remove.