ui: Improve reporting of 'system-error' exceptions.

* guix/ui.scm (call-with-error-handling): Change 'system-error' handler
  to display the error message as it was raised.

gnu: xpdf: Build sequentially.

* gnu/packages/pdf.scm (xpdf)[arguments]: Add #:parallel-build? #f.

gnu: lsh: Build with Readline 6.2.

* gnu/packages/lsh.scm (lsh): Use READLINE-6.2 instead of READLINE.

gnu: gdb: Disable tests.

* gnu/packages/gdb.scm (gdb): Disable tests.

gnu: valgrind: Adjust patch for glibc 2.19.

* gnu/packages/patches/valgrind-glibc.patch: s/2.18/2.19/.

union: Ensure that the output is always a directory.

Fixes the creation of single-package profiles, reported by Ludovic Courtès.

* guix/build/union.scm (union-build): Add new internal procedure
  'union-of-directories' that always creates a directory, containing the code
  previously used only to merge multiple directories.  Call it from the
  multiple-directory case in 'union' and from the top-level 'union-build'.

pki: Introduce 'write-acl', and fix wrong conversion in 'ensure-acl'.

* guix/pki.scm (write-acl): New procedure.
  (ensure-acl): Use it.  Fixes a regression introduced in 39831f1,
  whereby 'ensure-acl' would yield a wrong-type-arg error.
* guix/scripts/archive.scm (authorize-key): Use 'write-acl'.

build: Remove now useless Boost headers.

* daemon.am (libformat_headers): Remove 6 nix/boost files that were
  removed in Nix commit 1c2550a2ae826c422cf6d34f1c5c3e687474929d.

Update 'nix-upstream' sub-module.

* nix-upstream: Update.
* daemon.am (AM_CXXFLAGS): Add -std=c++0x.

doc: Update description of the chroot contents.

* doc/guix.texi (Build Environment Setup): Adjust description of /dev
  and /proc; remove footnote about /dev/shm, now obsolete.

offload: Prevent the '.drv' and build result from being GC'd.

Before that, there was a small time window during which the GC could
wipe the .drv (before 'guix build' has been called), or the build
result (before 'retrieve-files' has started.)

* guix/scripts/offload.scm (remote-pipe): Add #:quote? parameter and
  honor it.
  (%gc-root-file): New variable.
  (register-gc-root, remove-gc-root): New procedures.
  (offload): Adjust comment.  Run 'guix build' with '-r %GC-ROOT-FILE'.
  (transfer-and-offload): Call 'register-gc-root' before
  sending (derivation-file-name DRV).  Call 'remove-gc-root' after the
  call to 'offload' or 'retrieve-files'.
  (send-files): Call 'remote-pipe' with #:quote? #f.
  (retrieve-files): Likewise.

gnu: parted: Build against Readline 6.2.

* gnu/packages/readline.scm (readline-6.2): New variable.
* gnu/packages/parted.scm (parted): Use it instead of READLINE.

gnu: inkscape: Use libgc 7.2.

* gnu/packages/inkscape.scm (inkscape): Use LIBGC-7.2 instead of LIBGC.

gnu: python: Use /nix/.../sh in popen2 module

* gnu/packages/python.scm (python-2): patch Lib/popen2.py to use /nix/.../sh.

gnu: global: Upgrade to 6.2.12.

* gnu/packages/global.scm (global): Upgrade to 6.2.12.

gnu: apl: Upgrade to 1.3.

* gnu/packages/apl.scm (apl): Upgrade to 1.3.

gnu: xorriso: Upgrade to 1.3.6.pl01.

* gnu/packages/cdrom.scm (xorriso): Upgrade to 1.3.6.pl01.

gnu: gxmessage: Upgrade to 2.20.1.

* gnu/packages/gxmessage.scm (gxmessage): Upgrade to 2.20.1.

gnu: help2man: Upgrade to 1.45.1.

* gnu/packages/help2man.scm (help2man): Upgrade to 1.45.1.

gnu: zile: Upgrade to 2.4.11.

* gnu/packages/zile.scm (zile): Upgrade to 2.4.11.