gnu: ghostscript: Support cross-compilation.

* gnu/packages/ghostscript.scm (ghostscript)[arguments]: Pass "CCAUX"
and "--enable-save_confaux" to #:configure-flags.  Add 'add-native-lz'
phase when cross-compiling.
[native-inputs]: Add ZLIB, LIBJPEG, and LCMS when cross-compiling.

gnu: grub: Fix build failure with recent flex.

* gnu/packages/flex.scm (flex-2.6.1): New variable.
* gnu/packages/bootloaders.scm (grub)[native-inputs]: Use flex-2.6.1.

gnu: wayland-protocols: Update to 1.9.

* gnu/packages/freedesktop.scm (wayland-protocols): Update to 1.9.

gnu: ncmpcpp: Update to 0.8.

* gnu/packages/mpd.scm (ncmpcpp): Update to 0.8.
[inputs]: Add curl.
[source], [home-page]: Use HTTPS URLs.

Merge branch 'master' into core-updates

gnu: libtiff: Fix two integer overflows.

* gnu/packages/patches/libtiff-tiffycbcrtorgb-integer-overflow.patch,
gnu/packages/patches/libtiff-tiffycbcrtorgbinit-integer-overflow.patch:
New files.
* gnu/local.mk (dist_patch_DATA): Add them.
* gnu/packages/image.scm (libtiff-4.0.8)[source]: Use them.

gnu: ncurses: Fix CVE-2017-10684 and CVE-2017-10685.

* gnu/packages/patches/ncurses-CVE-2017-10684-10685.patch: New file.
* gnu/local.mk (dist_patch_DATA): Add it.
* gnu/packages/ncurses.scm (ncurses)[replacement]: New field.
(ncurses/fixed): New variable.

gnu: poppler: Fix null pointer dereferences.

* gnu/packages/patches/poppler-fix-crash-with-broken-documents.patch: New
file.
* gnu/local.mk (dist_patch_DATA): Add it.
* gnu/packages/pdf.scm (poppler/fixed)[source]: Add the patch.

gnu: emacs-exwm-x: Update to 1.7.2.

* gnu/packages/emacs.scm (emacs-exwm-x): Update to 1.7.2.
[propagated-inputs]: Add emacs-use-package.

Signed-off-by: Arun Isaac <arunisaac@systemreboot.net>

gnu: ghostscript: Make "/CreationDate", "/ModDate" optional, depending on environment variable.

* gnu/packages/patches/ghostscript-no-header-creationdate.patch: New file.
* gnu/local.mk (dist_patch_DATA): Add it.
* gnu/packages/ghostscript.scm (ghostscript): Use it.

gnu: ghostscript: Make XMP UUID headers optional, depending on environment variable.

* gnu/packages/patches/ghostscript-no-header-uuid.patch: New file.
* gnu/local.mk (dist_patch_DATA): Add it.
* gnu/packages/ghostscript.scm (ghostscript): Use it.

gnu: ghostscript: Make "/ID" optional, depending on environment variable.

* gnu/packages/patches/ghostscript-no-header-id.patch: New file.
* gnu/local.mk (dist_patch_DATA): Add it
* gnu/packages/ghostscript.scm (ghostscript): Use it.

gnu: unshield: Remove incorrect '"'.

* gnu/packages/compression.scm (unshield): Remove incorrect '"'.

build, vm: Use "GuixSD" or "GUIXSD" as volume label.

* gnu/build/vm.scm (initialize-hard-disk): Use "GuixSD" as label.
* gnu/system/install.scm (installation-os): Use "GuixSD" as label.
* gnu/system/vm.scm (system-disk-image): Use "GuixSD" or "GUIXSD" as volume
label.

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

gnu: Add et.

* gnu/packages/ssh.scm (et): New variable.

Signed-off-by: Ludovic Courtès <ludo@gnu.org>

gnu: groff: Remove timestamps.

Fixes <https://bugs.gnu.org/27593>.

* gnu/packages/patches/groff-source-date-epoch.patch: New file.
* gnu/local.mk: Add it.
* gnu/packages/groff.scm (groff)[source]: Add it.

daemon: Allow compilation with GCC 4.9.

Reported by Ricardo Wurmus.

* nix/nix-daemon/nix-daemon.cc (acceptConnection): Remove intermediate
'inaddr' variables that relied on implicit casts.  This fixes
compilation with GCC 4.9.

gnu: libpciaccess: Refer to 'pci.ids' from pciutils.

Prior to this change libpciaccess would try to read from
/usr/share/hwdata/pci.ids.

* gnu/packages/xorg.scm (libpciaccess)[arguments]: New field.
[inputs]: Add PCIUTILS.

gnu: pciutils: Tweak description.

* gnu/packages/pciutils.scm (pciutils)[description]: Use @command.

gnu: pciutils: Move 'pci.ids.gz' to 'share/hwdata'.

* gnu/packages/pciutils.scm (pciutils)[arguments] <configure>: Set
'IDSDIR' such that 'pci.ids.gz' goes to share/hwdata.