gnu: grep: Update to 2.21.

* gnu/packages/base.scm (grep): Update to 2.21.

build-system/gnu: Gracefully handle dangling symlinks in the 'strip' phase.

* guix/build/gnu-build-system.scm (strip): Check whether 'file-exists?'
  before calling 'elf-file?' and 'ar-file?'.  This should fix build
  failures in the presence of dangling symlinks, as in
  <http://hydra.gnu.org/build/167521/nixlog/1/raw>.

utils: 'elf-file?' and 'ar-file?' return #f for directories.

This avoids uncaught exceptions when the 'strip' phase would call these
procedures on symlinks to directories, such as 'lib/terminfo' in
ncurses (see <http://hydra.gnu.org/build/167310/nixlog/1/tail-reload>.)

* guix/build/utils.scm (file-header-match): Catch 'system-error', and
  return #f upon EISDIR.

utils: Turn 'parallel-job-count' into a parameter.

* guix/build/utils.scm (parallel-job-count): Turn into a SRFI-39 parameter.

build-system/gnu: Strip 'ar' archives as well.

* guix/build/gnu-build-system.scm (strip): Also strip when (ar-file?
  PATH) is true.

utils: Factorize magic bytes detection.

* guix/build/utils.scm (file-header-match): New procedure.
  (%elf-magic-bytes): New variable.
  (elf-file?, ar-file?): Define using 'file-header-match'.

utils: Add 'ar-file?'.

* guix/build/utils.scm (%ar-magic-bytes): New variable.
  (ar-file?): New procedure.

build-system/gnu: Strip only ELF files.

Suggested by Mark H Weaver <mhw@netris.org>
at <http://lists.gnu.org/archive/html/guix-devel/2014-10/msg00395.html>.

* guix/build/gnu-build-system.scm (strip)[strip-dir]: Strip only
  when (elf-file? PATH) is true.

utils: Add 'elf-file?'.

* guix/build/utils.scm (elf-file?): New procedure.

utils: Export 'parallel-job-count'.

* guix/build/utils.scm (parallel-job-count): New procedure.
* guix/build/gnu-build-system.scm (%parallel-job-count): Remove.
  (build, check): Use 'parallel-job-count' instead.

gnu: pkg-config: Update to 0.28.

* gnu/packages/pkg-config.scm (%pkg-config): Update to 0.28.

gnu: file: Update to 5.20.

* gnu/packages/file.scm (file): Update to 5.20.
  (file-5.20): Remove.
* gnu/packages/patches/file-CVE-2014-3587.patch: Remove.
* gnu-system.am (dist_patch_DATA): Adjust accordingly.
* gnu/packages/patchutils.scm (quilt): Use FILE instead of FILE-5.20.
* gnu/packages/version-control.scm (aegis): Ditto.

gnu: Add AVR-Libc.

* gnu/packages/avr.scm: New file.
* gnu-system.am (GNU_SYSTEM_MODULES): Add avr.scm.
* gnu/packages/cross-base.scm (xgcc-avr): New variable.
* gnu/packages/bootstrap.scm (glibc-dynamic-linker): Add case for
  "avr".

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

doc: Fix typos regarding 'lsh-service'.

Reported by Adam Pribyl <pribyl@lowlevel.cz>.

* doc/guix.texi (Using the Configuration System): Use #:root-login?, not
  #:allow-root-login?, in example.
  (Networking Services): Fix module name for ssh.

gnu: Add hexchat.

* gnu/packages/messaging.scm (hexchat): New variable.

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

gnu: libxkbcommon: Update to 0.5.0.

* gnu/packages/qt.scm (libxkbcommon): Update to 0.5.0.
    Add input libxcb and native input pkg-config.

gnu: xcb-util-renderutil: Update to 0.3.9.

* gnu/packages/xorg.scm (xcb-util-renderutil): Update to 0.3.9.

gnu: xcb-util-keysyms: Update to 0.4.0.

* gnu/packages/xorg.scm (xcb-util-keysyms): Update to 0.4.0.

gnu: xcb-util-image: Update to 0.4.0.

* gnu/packages/xorg.scm (xcb-util-image): Update to 0.4.0.

gnu: xcb-util: Update to 0.4.0.

* gnu/packages/xorg.scm (xcb-util): Update to 0.4.0.