gnu: Add toolchain support for 'armhf-linux'.

Based on preliminary work by John Darrington <john@darrington.wattle.id.au>.

* gnu/packages/cross-base.scm (xgcc-armhf): New variable.
* gnu/packages/gcc.scm (gcc-configure-flags-for-triplet): Add armhf case.
  (gcc-4.7)[pre-configure]: Add gcc/config/*/linux-eabi.h to the list
  of files in which to patch GLIBC_DYNAMIC_LINKER.
* gnu/packages/bootstrap.scm (glibc-dynamic-linker): Add armhf case.
* guix/utils.scm (gnu-triplet->nix-system, nix-system->gnu-triplet):
  Add armhf cases.

gnu: patchelf: On ARM, apply experimental patch to get it working.

* gnu/packages/patches/patchelf-rework-for-arm.patch: New file.
* gnu-system.am: Add it.
* gnu/packages/elf.scm: Apply patch when the target is ARM.

gnu: gmp: Apply fixes for armhf.

* gnu/packages/patches/gmp-arm-asm-nothumb.patch: New file.
* gnu-system.am (dist_patch_DATA): Add it.
* gnu/packages/multiprecision.scm (gmp): Add patch.  Include --build triplet
  in configure args when building natively.
* gnu/packages/commencement.scm (gcc-final): Use bootstrap guile to
  build gmp-source.

gnu: gcc: Use 'gcc-configure-flags-for-triplet' for native compilers too.

* gnu/packages/gcc.scm (gcc-configure-flags-for-triplet): Do not export it.
  (gcc-4.7): Pass the result of 'gcc-configure-flags-for-triplet' to configure
  for all builds, including native ones.
* gnu/packages/cross-base.scm (cross-gcc-arguments): Do not add the result of
  'gcc-configure-flags-for-triplet' here, since it is now included in the
  configure-flags inherited from gcc-4.8.

Move 'nix-system->gnu-triplet' to (guix utils) and export it.

* gnu/packages/commencement.scm (nix-system->gnu-triplet): Move to...
* guix/utils.scm (nix-system->gnu-triplet): ... here.  Fix docstring typo.

gnu: gcc-static: Remove -lgcc_s from GNU_USER_TARGET_LIB_SPEC.

* gnu/packages/make-bootstrap.scm (%gcc-static): Add 'remove-lgcc_s
  phase.
* gnu/packages/gcc.scm (gcc-4.7): Add comment.

gnu: bootstrap: Fix egrep and fgrep after unpacking bootstrap binaries.

* gnu/packages/bootstrap.scm (%bootstrap-coreutils&co): Add #:snippet argument
  to 'package-from-tarball' that calls 'patch-shebang' on egrep and fgrep
  after unpacking.  Test 'fgrep' instead of 'true'.

gnu: bootstrap: Add support for snippets to 'package-from-tarball'.

* gnu/packages/bootstrap.scm (package-from-tarball): Add new keyword
  argument #:snippet.

gnu: tcl: Pass --mandir to configure.

This partially reverts 9b1bf33081652210502c6ef34506e27a9bc60f06.
"gnu: Remove a bunch of now unneeded '--mandir' configure flags."

* gnu/packages/tcl.scm (tcl)[arguments]: Put back the --mandir configure flag,
  with a comment explaining why it's still needed.

gnu: Make libtool and libltdl completely separate.

* gnu/packages/autotools.scm (libtool)[outputs]: Remove.
  [arguments]: Remove 'if' around arguments.  Add #:configure-flags.
* gnu/packages/apr.scm (apr)[inputs]: Change libtool to libltdl.
* gnu/packages/fontutils.scm (libuninameslist)[native-inputs]: Remove
  "libtool-bin".
* gnu/packages/global.scm (global): Change libtool to libltdl.
* gnu/packages/gnunet.scm (libextractor, gnunet): Likewise.
* gnu/packages/graphviz.scm (graphviz): Likewise.
* gnu/packages/libcanberra.scm (libcanberra): Likewise.
* gnu/packages/libevent.scm (libuv)[native-inputs]: Remove "bin" part
  for libtool.
* gnu/packages/mail.scm (mailutils): Change libtool to libltdl.
  (libetpan): Remove "bin" part for libtool.
* gnu/packages/mp3.scm (libmp3splt): Change libtool to libltdl.
* gnu/packages/openldap.scm (openldap): Remove "bin" part of libtool.
  Move it from 'inputs' to 'native-inputs'.
* gnu/packages/photo.scm (libgphoto2): Change libtool to libltdl.
* gnu/packages/pulseaudio.scm (pulseaudio): Likewise.
* gnu/packages/ssh.scm (guile-ssh): Remove "bin" part of libtool.
* gnu/packages/web.scm (libpsl): Likewise.
* gnu/packages/weechat.scm (weechat): Move libtool to 'native-inputs'
  and add libltdl to 'inputs'.

gnu: libtool: Update to 2.4.4.

* gnu/packages/patches/libtool-2.4-skip-tests.patch: Rename to...
* gnu/packages/patches/libtool-skip-tests.patch: ... this.
* gnu/packages/patches/libtool-skip-tests-for-mips.patch: Remove.
* gnu-system.am (dist_patch_DATA): Adjust accordingly.
* gnu/packages/autotools.scm (libtool): Update to 2.4.4.
  (libtool-2.4.4): Remove.

gnu: guile: Depend on 'libltdl' rather than 'libtool'.

* gnu/packages/guile.scm (guile-1.8, guile-2.0): Replace LIBTOOL with
  LIBLTDL.

gnu: libtool: Add libltdl as a separate package.

* gnu/packages/autotools.scm (libltdl): New variable.

gnu: libtool: Use 'parallel-job-count' to get the argument for '-j'.

* gnu/packages/autotools.scm (libtool)[arguments] <check>:
  Use (parallel-job-count) instead of hand-written code.

Revert "gnu: gcc: Add '-lgcc_s' only when '-pthread' is given."

This reverts commit 9097e666d48c9b6c0263dcbe60b5af69ff7689f4.

This turned out not to be a good strategy.  Some build system, e.g. tcl's, do
not pass -pthread on GNU/Linux by default, but merely link with -lpthread.
Also, Ludovic found other cases where libgcc_s is dlopened by libc that have
nothing to do with pthreads, e.g. to walk the stack.

gnu: guile: Apply fixes for arm.

* gnu/packages/patches/guile-arm-fixes.patch: New file.
* gnu-system.am (dist_patch_DATA): Add it.
* gnu/packages/guile.scm (guile-2.0): Add patch.

gnu: gcc: Add '-lgcc_s' only when '-pthread' is given.

Suggested by Ludovic Courtès <ludo@gnu.org>.

* gnu/packages/gcc.scm (gcc-4.7): In our modified GNU_USER_TARGET_LIB_SPEC,
  add '-lgcc_s' only when '-pthread' is given.

gnu: gcc: Improve dynamic linker patching code.

* gnu/packages/gcc.scm (gcc-4.7): Join multi-line definitions of
  GLIBC_DYNAMIC_LINKER* before attempting substitutions.
  (gcc-4.9)[arguments]: Remove arguments override.

gnu: patchelf: Update to 0.8.

* gnu/packages/elf.scm (patchelf): Update to 0.8.
* gnu/packages/patches/patchelf-page-size.patch: Adapt to new version.

gnu: bash: Update to 4.3.33.

* gnu/packages/bash.scm (%patch-series-4.3): Add patches 31-33.