gnu: sdl: Fix incompatibility with libx11-1.6.

* gnu/packages/patches/sdl-libx11-1.6.patch: New file
* gnu-system.am (dist_patch_DATA): Add it.
* gnu/packages/sdl.scm (sdl): Add patch.

gnu: gtkglext: Add glu to inputs.

* gnu/packages/gnome.scm (gtkglext): Add glu to inputs.

gnu: ntp: Update to 4.2.8.

* gnu/packages/ntp.scm (ntp): Update to 4.2.8.  Add openssl to inputs.
  Add pkg-config to native-inputs.  Change source URI to archive.ntp.org.

Merge branch 'master' into xorg-updates

Revert "gnu: matplotlib: Comment out python2-matplotlib."

This reverts commit afc720d34c43a2fcf0b5871226c15ad6c5f73697.

build-system/python: Fix 'package-with-explicit-python'.

Reported by Federico Beffa <beffa@ieee.org>
and Eric Bavier <ericbavier@gmail.com>.

* guix/build-system/python.scm (package-with-explicit-python): Do
  nothing when P's build system is not PYTHON-BUILD-SYSTEM.

gnu: matplotlib: Comment out python2-matplotlib.

* gnu/packages/python.scm (python2-matplotlib, python2-scipy, python2-numpy):
  Comment out python2-matplotlib and the packages making use of it as the
  generation of the derivation of these packages takes very long.

Optimize package-transitive-supported-systems.

* guix/packages.scm (first-value): Remove.
  (define-memoized/v): New macro.
  (package-transitive-supported-systems): Rewrite.

packages: Sort Scheme file lists used by 'fold-packages'.

* gnu/packages.scm (scheme-files): Call 'sort' on result.

Merge branch 'master' into xorg-updates

Really remove the 'nix-upstream' submodule.

* nix-upstream: Remove subproject.

gnu: Add xfce4-terminal.

* gnu/packages/xfce.scm (xfce4-terminal): New variable.

gnu: Add vte.

* gnu/packages/gnome.scm (vte, vte/gtk+-2): New variables.

gnu: Consistently use modular xorg source URIs in xorg.scm.

* gnu/packages/xorg.scm (bigreqsproto, compositeproto, damageproto)
  (dmxproto, encodings, font-adobe100dpi, font-adobe75dpi, font-alias)
  (font-arabic-misc, font-cronyx-cyrillic, font-dec-misc, font-isas-misc)
  (font-micro-misc, font-misc-cyrillic, font-misc-ethiopic, font-misc-misc)
  (font-mutt-misc, font-schumacher-misc, font-screen-cyrillic, font-sony-misc)
  (font-sun-misc, font-util, font-winitzki-cyrillic, font-xfree86-type1)
  (libpthread-stubs, libwindowswm, libxdmcp, libxkbfile, libxscrnsaver)
  (luit, recordproto, renderproto, resourceproto, scrnsaverproto, setxkbmap)
  (smproxy, windowswmproto, x11perf, xcb-proto, xcmiscproto, xcmsdb, xdriinfo)
  (xf86-input-void, xf86-video-newport, xf86bigfontproto, xf86dgaproto)
  (xf86driproto, xf86vidmodeproto, xgamma, xineramaproto, xkbevd, xlsatoms)
  (xorg-sgml-doctools, xpr, xwud, fixesproto, mkfontdir, libxcb, xcb-util)
  (xcb-util-image, xcb-util-keysyms, xcb-util-renderutil, kbproto, xbitmaps):
  Use source URIs with prefix mirror://xorg/individual/ for consistency.
  (dri3proto, presentproto, printproto): Remove comments about them not
  being part of X11R7.7.

gnu: xorg-server: Update to 1.16.2.901, with many security fixes.

Includes fixes for CVE-2014-8091, CVE-2014-8092, CVE-2014-8093, CVE-2014-8094,
CVE-2014-8095, CVE-2014-8096, CVE-2014-8097, CVE-2014-8098, CVE-2014-8099,
CVE-2014-8100, CVE-2014-8101, CVE-2014-8102, and CVE-2014-8103.

See <http://www.x.org/wiki/Development/Security/Advisory-2014-12-09/>

* gnu/packages/xorg.scm (xorg-server): Update to 1.16.2.901.  Move mesa,
  resourceproto, scrnsaverproto, and xf86driproto from inputs to
  propagated-inputs.  Add dri3proto and presentproto to propagated-inputs.
  Add eudev and libxshmfence to inputs.  Add a 'pre-configure' phase instead
  of modifying the 'configure' phase.  Adapt substitution that avoids trying
  to 'mkdir /var' to build system changes.

* gnu/services/xorg.scm (xserver.conf): Add xf86-input-evdev ModulePath line.

gnu: xf86-video-voodoo: Update to 1.2.5.

* gnu/packages/xorg.scm (xf86-video-voodoo): Update to 1.2.5.

gnu: xf86-video-vmware: Update to 13.0.2.

* gnu/packages/patches/xf86-video-vmware-glibc-2.20.patch: New file.
* gnu-system.am (dist_patch_DATA): Add it.
* gnu/packages/xorg.scm (xf86-video-vmware): Update to 13.0.2.
  Add patch.  Add mesa to inputs.

gnu: xf86-video-vesa: Update to 2.3.3.

* gnu/packages/xorg.scm (xf86-video-vesa): Update to 2.3.3.

gnu: xf86-video-trident: Update to 1.3.6.

* gnu/packages/patches/xf86-video-trident-remove-mibstore.patch: New file.
* gnu-system.am (dist_patch_DATA): Add it.
* gnu/packages/xorg.scm (xf86-video-trident): Update to 1.3.6.  Add patch.

gnu: xf86-video-tga: Update to 1.2.2.

* gnu/packages/patches/xf86-video-tga-remove-mibstore.patch: New file.
* gnu-system.am (dist_patch_DATA): Add it.
* gnu/packages/xorg.scm (xf86-video-tga): Update to 1.2.2.  Add patch.