packages: Add 'armhf-linux' to '%hydra-supported-systems'.

* guix/packages.scm (%hydra-supported-systems): Do not remove 'armhf-linux'
  from it.  It is now equal to '%supported-systems'.

gexp: Remove duplicate 'mkdir-p' definition.

* guix/gexp.scm (%mkdir-p-definition): Remove.
  (%utils-module): New variable.
  (imported-files, compiled-modules): Have gexp load %UTILS-MODULE
  instead of using %MKDIR-P-DEFINITION.

gnu: coreutils: Add dependency on libcap.

* gnu/packages/base.scm (coreutils)[inputs]: Add LIBCAP.

gnu: libcap: Update to 2.24.

* gnu/packages/linux.scm (libcap): Update to 2.24.  Fetch the source
  from mirror://kernel.org.

gnu: glibc: Upgrade to 2.22.

* gnu/packages/base.scm (glibc): Upgrade to 2.22.
  (coreutils-light): New variable.
* gnu/packages/commencement.scm (locale-proof-package): New procedure.
  (%boot5-inputs): Add LD-WRAPPER, BINUTILS-FINAL, BASH-FINAL, GNU-MAKE,
  DIFFUTILS, FINDUTILS, COREUTILS-LIGHT (pass through
  'new-libc-package'), and %BOOTSTRAP-COREUTILS&CO (passed through
  'locale-proof-package'.)

utils: Move 'package-name->name+version' to (guix build utils).

* guix/utils.scm (package-name->name+version): Move to...
* guix/build/utils.scm (package-name->name+version): ... here.  New
  procedure.
* guix/build/emacs-build-system.scm (package-name->name+version):
  Remove.

utils: Add 'strip-store-file-name'.

* guix/build/utils.scm (strip-store-file-name): New procedure.
* guix/build/emacs-build-system.scm (store-directory->name-version):
  Remove.  Update callers to use 'strip-store-file-name'.
* gnu/packages/gcc.scm (make-libstdc++-doc)[arguments]: Use
  'strip-store-file-name' instead of 'string-drop'.

gnu: glibc: _PATH_BSHELL refers to our static bash.

* gnu/packages/base.scm (glibc)[arguments]: Change _PATH_BSHELL in
  paths.h to refer to STATIC-BASH.

gnu: glibc: Use 'modify-phases'.

* gnu/packages/base.scm (glibc)[arguments]: Use 'modify-phases' instead
  of 'alist-cons-before'.

build-system/gnu: Use monotic time to measure elapsed time.

* guix/build/gnu-build-system.scm (gnu-build)[elapsed-time]: New
  procedure.
  Use it, and use (current-time time-monotonic) instead
  of (gettimeofday).  Show one digit after the comma for the elapsed
  time.

gnu: ncurses: Really install headers to OUT/include.

* gnu/packages/ncurses.scm (ncurses)[arguments]: Pass --enable-overwrite.

gnu: Use 'install-file' instead of 'mkdir-p' and 'copy-file' in obvious cases.

* gnu/packages/bioinformatics.scm (bedtools, bowtie, bwa, hisat, samtools,
  plink, star): Use 'install-file' instead of 'mkdir-p' + 'copy-file'.
* gnu/packages/check.scm (catch-framework): Likewise.
* gnu/packages/code.scm (global): Likewise.
* gnu/packages/emacs.scm (magit-svn, haskell-mode, emacs-pdf-tools):
  Likewise.
* gnu/packages/engineering.scm (fastcap, fasthenry): Likewise.
* gnu/packages/gnuzilla.scm (nss): Likewise.
* gnu/packages/guile.scm (guile-minikanren): Likewise.
* gnu/packages/java.scm (swt): Likewise.
* gnu/packages/make-bootstrap.scm (%static-binaries): Likewise.
* gnu/packages/maths.scm (lpsolve): Likewise.
* gnu/packages/mp3.scm (mpc123): Likewise.
* gnu/packages/ninja.scm (ninja): Likewise.
* gnu/packages/python.scm (python-numpy, python-pyparsing): Likewise.
* gnu/packages/screen.scm (dtach): Likewise.
* gnu/packages/synergy.scm (synergy): Likewise.
* gnu/packages/textutils.scm (utf8proc): Likewise.
* gnu/packages/version-control.scm (git-test-sequence): Likewise.
* gnu/packages/wicd.scm (wicd): Likewise.

utils: Add 'install-file'.

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

gnu: glibc: Do not copy static Bash binary to bin/.

This avoids problems when installing 'glibc' in a profile, where glibc's
limited 'bash' would take precedence over the valid 'bash'.

* gnu/packages/base.scm (glibc)[arguments]: Do not copy STATIC-BASH to
  OUT/bin.  Instead, simply refer to it directly.
  [inputs]: Use STATIC-BASH instead of BASH-LIGHT.
* gnu/packages/commencement.scm (static-bash-for-glibc): Likewise.
  (glibc-final)[arguments]: Add STATIC-BASH-FOR-GLIBC to
  #:allowed-references.
  (gcc-final)[arguments]: Likewise.
  [native-inputs]: Add "static-bash".

gnu: ncurses: Remove obsolete hack.

* gnu/packages/ncurses.scm (ncurses)[arguments]: Remove obsolete Solaris
  hack.

gnu: ncurses: Rework trick to avoid reference to the bootstrap bash.

This removes reliance on the availability of 'bin/sh' in glibc.

* gnu/packages/ncurses.scm (ncurses): Remove 'configure-phase'.  Add
  'remove-shebang-phase'.
  [arguments]: Remove distinction between cross builds and native builds.  Use
  'modify-phases'.  Add 'remove-unneeded-shebang' phase.

gnu: ncurses: Upgrade to 6.0.

* gnu/packages/ncurses.scm (ncurses): Upgrade to 6.0.  Change library names to
  '.so.6'.

gnu: binutils: Upgrade to 2.25.1.

* gnu/packages/base.scm (binutils): Upgrade to 2.25.1.

gnu: Add 'bash-static'.

* gnu/packages/bash.scm (static-bash): New variable.

download: Keep only 2 store items for all the downloads.

This significantly reduces churn in the store.  It also reduces run time
of 'guix build inkscape -Sd' by ~10%.

* guix/download.scm (url-fetch)[mirror-file]: New variable.
  [builder]: Get URL from the "guix download url" env. var.  Get the mirrors
  from MIRROR-FILE.  Pass #:script-name and #:env-vars to 'gexp->derivation'.