gnu: Add Corkscrew 2.0.

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

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

gnu: guile-ssh: Remove now unneeded cruft.

* gnu/packages/ssh.scm (guile-ssh): Remove libssh version hack from
  'autoreconf' phase.

gnu: libgcrypt: Make old version 1.5.3 public.

* gnu/packages/gnupg.scm (libgcrypt-1.5): New variable.
* gnu/packages/ssh.scm (libssh): Use libgcrypt-1.5 instead of defining it
    ad-hoc.

gnu: libssh: Upgrade to 0.5.5.

* gnu/packages/ssh.scm (libssh): Upgrade to 0.5.5.

gnu: libssh: Build against an older libgcrypt.

* gnu/packages/ssh.scm (libssh): Use libgcrypt 1.5.3 as an input.

gnu: Move libelf and patchelf to (gnu packages elf).

* gnu/packages/patchelf.scm (patchelf): Move to...
* gnu/packages/elf.scm (patchelf): ... here.
* gnu/packages/patchelf.scm: Remove.
* gnu-system.am (GNU_SYSTEM_MODULES): Adjust accordingly.
* gnu/packages/gcc.scm (libelf): Move to...
* gnu/packages/elf.scm (libelf): ... here.
* gnu/packages/cdrom.scm, gnu/packages/icu4c.scm,
  gnu/packages/samba.scm, gnu/packages/scheme.scm, gnu/packages/ssh.scm:
  Adjust references to (gnu packages patchelf).

gnu: Move 'guile-ssh' to (gnu packages ssh).

Reported by John Darrington <john@darrington.wattle.id.au>.

* gnu/packages/guile.scm (guile-ssh): Move to...
* gnu/packages/ssh.scm (guile-ssh): ... here.  New variable.
  This fixes a circular dependency issue, as reported at
  <https://lists.gnu.org/archive/html/guix-devel/2013-12/msg00024.html>.

gnu: libssh: Add $libdir to RUNPATH of libssh_threads.so.

* gnu/packages/ssh.scm (libssh)[arguments]: Add #:phases, #:modules, and
  #:imported-modules.
  [native-inputs]: New field.

gnu: Add libssh.

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

gnu: Add openssh.

* gnu/packages/ssh.cm (openssh): New variable.

gnu: Add libssh2.

* gnu/packages/ssh.scm: New file.
* Makefile.am (MODULES): Add it.