gnu: Fix memcached service startup.

Memcached changes to the memcached user from root before writing the PID
file. This means that it must be able to write the PID file as the memcached
user.

To make this work, create the /var/run/memcached directory when the service
starts, make it owned by memcached, and change memcached to write the PID file
to /var/run/memcached/pid.

This wasn't picked up by the system test as the "service running" part was too
permissive, and only failed on an error. Instead, test the response from
calling start-service and check that the PID is a number.

* gnu/services/databases.scm (memcached-activation): New variable.
  (memcached-shepherd-service): Change PID file location.
  (memcached-service-type): Extend the activation-service-type.
* gnu/tests/databases.scm (run-memcached-test)[test]: Change the "service
  running" test to check the response from the shepherd.

gnu: Add dssi.

* gnu/packages/music.scm (dssi): New variable.

gnu: Add emacs-highlight-symbol.

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

Signed-off-by: Marius Bakke <mbakke@fastmail.com>

gnu: fish-guix: Use new download URL.

* gnu/packages/shells.scm (fish-guix)[source]: Adjust the download URL.

Signed-off-by: Marius Bakke <mbakke@fastmail.com>

gnu: p11-kit: Update to 0.23.8.

* gnu/packages/tls.scm (p11-kit): Update to 0.23.8.

gnu: signify: Update to 22.

* gnu/packages/crypto.scm (signify): Update to 22.

gnu: diamond: Update to 0.9.10.

* gnu/packages/bioinformatics.scm (diamond): Update to 0.9.10.

gnu: bcftools: Fix building on aarch64.

* gnu/packages/patches/bcftools-regidx-unsigned-char.patch: New file.
* gnu/packages/bioinformatics.scm (bcftools)[source]: Use it.
* gnu/local.mk (dist_patch_DATA): Register it.

Revert "gnu: pspp: Update to 0.11.0."

This FTBFS on x86_64 and i686.

This reverts commit f4c808df5b99bbe6d7a307c69ad27da5b17703d1.

gnu: youtube-dl: Update to 2017.08.13.

* gnu/packages/video.scm (youtube-dl): Update to 2017.08.13.

gnu: e2fsprogs: Update to 1.43.5.

* gnu/packages/patches/e2fsprogs-32bit-quota-warnings.patch: New file.
* gnu/local.mk (dist_patch_DATA): Register it.
* gnu/packages/linux.scm (e2fsprogs): Update to 1.43.5.
[source]: Use patch.

gnu: cvs: Fix CVE-2017-12836.

* gnu/packages/patches/cvs-2017-12836.patch: New file.
* gnu/local.mk (dist_patch_DATA): Add it.
* gnu/packages/version-control.scm (cvs)[source]: Use it.

gnu: git@2.10: Update to 2.10.4 [fixes CVE-2017-1000117].

...also disable tests, since they broke after c9f4f56b24801718d89c2520b.

* gnu/packages/version-control.scm (git@2.10): Update to 2.10.4.
[arguments]: New field.

gnu: gcc@7: Update to 7.2.0.

* gnu/packages/gcc.scm (gcc@7): Update to 7.2.0.
[source]: Switch to xz compression.

Revert "gnu: e2fsprogs: Update to 1.43.5."

Fails to build on i686:
<https://lists.gnu.org/archive/html/guix-devel/2017-08/msg00118.html>

This reverts commit 3ddaa7922bdd71ff4467b95a7ed264bbc4d49975.

gnu: milkytracker: Update to 1.01.00.

* gnu/packages/music.scm (milkytracker): Update to 1.01.00.

gnu: Add bismark.

* gnu/packages/bioinformatics.scm (bismark): New variable.

gnu: Add r-dexseq.

* gnu/packages/bioinformatics.scm (r-dexseq): New variable.

gnu: Add perl-math-random-secure.

* gnu/packages/crypto.scm (perl-math-random-secure): New variable.

gnu: Add perl-crypt-random-source.

* gnu/packages/crypto.scm (perl-crypt-random-source): New variable.