gnu: Add emacs-esxml.

* gnu/packages/emacs.scm (emacs-esxml): New variable.

gnu: assword: Update to 0.11.

* gnu/packages/password-utils.scm (assword): Update to 0.11.

gnu: python-cffi: Update phase style.

* gnu/packages/libffi.scm (python-cffi)[arguments]: Substitute INVOKE
for SYSTEM*, end phases with #t, and remove unneeded bits from the
‘install-doc’ phase.

gnu: python-cffi: Update to 1.11.4.

* gnu/packages/libffi.scm (python-cffi): Update to 1.11.4.

gnu: perl-scalar-list-utils: Update to 1.50.

* gnu/packages/perl.scm (perl-scalar-list-utils): Update to 1.50.

gnu: Add nghttp2.

* gnu/packages/web.scm (nghttp2): New public variable.

gnu: ruby-ffi: Update to 1.9.22.

* gnu/packages/libffi.scm (ruby-ffi): Update to 1.9.22.

gnu: libpsl: Update to 0.20.0.

* gnu/packages/web.scm (libpsl): Update to 0.20.0.

gnu: Use HTTPS for supported freedesktop.org home pages.

* gnu/packages/fontutils.scm (fontconfig)[home-page]: Use HTTPS.
* gnu/packages/freedesktop.scm (python-pyxdg, accountsservice)
(modem-manager, telepathy-mission-control, telepathy-mission-control)
(colord-gtk, desktop-file-utils)[home-page]: Likewise.
* gnu/packages/ghostscript.scm (libspectre)[home-page]: Likewise.
* gnu/packages/glib.scm (dbus, dbus-glib, telepathy-glib)[home-page]:
Likewise.
* gnu/packages/gnome.scm (shared-mime-info, hicolor-icon-theme)
(libxklavier, colord, upower)[home-page]: Likewise.
* gnu/packages/gstreamer.scm (orc, python-gst)[home-page]: Likewise.
* gnu/packages/libcanberra.scm (sound-theme-freedesktop)[home-page]:
Likewise.
* gnu/packages/libreoffice.scm (libexttextcat)[home-page]: Likewise.
* gnu/packages/polkit.scm (polkit-gnome, polkit-gnome)[home-page]:
Likewise.
* gnu/packages/pulseaudio.scm (pavucontrol)[home-page]: Likewise.
* gnu/packages/python.scm (python-dbus)[home-page]: Likewise.
* gnu/packages/xdisorg.scm (startup-notification)[home-page]: Likewise.

gnu: polkit: Update phase & snippet style.

* gnu/packages/polkit.scm (polkit)[source]: End snippet with #t.
[arguments]: Substitute INVOKE for SYSTEM* and end phases with #t.

gnu: perl-xml-libxslt: Update to 1.96.

* gnu/packages/xml.scm (perl-xml-libxslt): Update to 1.96.

gnu: perl-net-smtp-ssl: Update to 1.04.

* gnu/packages/web.scm (perl-net-smtp-ssl): Update to 1.04.

gnu: perl-http-server-simple: Update to 0.52.

* gnu/packages/web.scm (perl-http-server-simple): Update to 0.52.

gnu: dvdstyler: Remove hard-coded version string.

* gnu/packages/cdrom.scm (dvdstyler)[arguments]: Remove a hard-coded
version string from the docbook-xsl search path.

gnu: libdvbpsi: Update to 1.3.2.

* gnu/packages/video.scm (libdvbpsi): Update to 1.3.2.

gnu: tinc: Update to 1.0.33.

* gnu/packages/vpn.scm (tinc): Update to 1.0.33.

gnu: gource: Update to 0.48.

* gnu/packages/version-control.scm (gource): Update to 0.48.

gnu: youtube-dl: Update to 2018.02.22.

* gnu/packages/video.scm (youtube-dl): Update to 2018.02.22.

gnu: libfilezilla: Update to 0.12.1.

* gnu/packages/ftp.scm (libfilezilla): Update to 0.12.1.

gnu: automake: Add 1.16.

* gnu/packages/autotools.scm (automake-1.16): New variable.