gnu: gcc: Prefer language-specific variables over 'CPATH'.

Suggested by Andy Wingo <wingo@igalia.com>.
Fixes <http://bugs.gnu.org/22186>.

* gnu/packages/gcc.scm (gcc-4.7)[native-search-paths]: Remove 'CPATH';
add 'C_INCLUDE_PATH' and 'CPLUS_INCLUDE_PATH' instead.
* gnu/packages/gcc.scm (custom-gcc): Add 'search-paths' parameter and
honor it.
(%generic-search-paths): New variable.
(gfortran-4.8, gfortran-4.9, gfortran, gfortran-5, gccgo-4.8): Pass
%GENERIC-SEARCH-PATHS to 'custom-gcc'.
(gcj)[native-search-paths]: New field.
(gcc-objc-4.8, gcc-objc++-4.8): Use 'OBJC_INCLUDE_PATH' and
'OBJCPLUS_INCLUDE_PATH', respectively.

gnu: commencement: Use GMP 6.0.0a for bootstrapping.

* gnu/packages/multiprecision.scm (gmp-6.0): New variable.
* gnu/packages/commencement.scm (gcc-boot0, gcc-final): Use it.
* gnu/packages/patches/gmp-arm-asm-nothumb.patch: New file, reinstated
from before e414a7d.
* gnu-system.am (dist_patch_DATA): Add it.

gnu: glibc: Remove timestamp from 'nscd' binary.

This makes libc bit-for-bit reproducible per '--rounds=2'.

* gnu/packages/base.scm (glibc)[arguments] <pre-configure>: Remove
__DATE__ and __TIME__ from nscd_stat.c.

gnu: pcre: Add "doc" output.

* gnu/packages/pcre.scm (pcre)[outputs]: New field.

gnu: util-linux: Do not build static libraries.

* gnu/packages/linux.scm (util-linux)[arguments]: Pass --disable-static.

gnu: gettext: Add "doc" output.

* gnu/packages/gettext.scm (gnu-gettext)[outputs]: New field.

gnu: ncurses: Add "doc" output.

* gnu/packages/ncurses.scm (ncurses)[outputs]: New field.
[arguments] <configure>: Replace standard 'configure' phase.
<remove-shebang-phase>: Remove "mandir=" line from 'ncursesw6-config'.

gnu: ncurses: Add 'TERMINFO_DIRS' search path variable.

* gnu/packages/ncurses.scm (ncurses)[native-search-paths]: New field.

gnu: bash: Add "doc" output.

* gnu/packages/bash.scm (bash)[outputs]: Add "doc" output.

gnu: grep: Add missing dependency on Perl.

* gnu/packages/base.scm (grep)[native-inputs]: New field.
* gnu/packages/commencement.scm (grep-final): Likewise.

gnu: bash: Update to patch level 42.

* gnu/packages/bash.scm (%patch-series-4.3): Add patches 40 to 42.

gnu: commencement: Initial Texinfo uses initial Perl.

* gnu/packages/commencement.scm (texinfo-boot0)[inputs]: Use
PERL-BOOT0.

gnu: perl: Build deterministically, and make byproducts deterministic.

With this, a --rounds=2 build passes, and timestamps in POD files can be
controlled with 'SOURCE_DATE_EPOCH'.

* gnu/packages/patches/perl-deterministic-ordering.patch,
gnu/packages/patches/perl-no-build-time.patch,
gnu/packages/patches/perl-source-date-epoch.patch: New files.
* gnu/packages/perl.scm (perl)[source]: Use them.
* gnu-system.am (dist_patch_DATA): Add them.

gnu: perl: Update to 5.22.0.

* gnu/packages/perl.scm (perl)[source]: Update to 5.22.0.  Remove
"perl-module-pluggable-search.patch" since Module::Pluggable appears to
be gone.
[arguments] <configure-phase>: Adjust Cwd.pm file name.  Replace
-std=c89 with -std=gnu89.
* gnu/packages/commencement.scm (perl-boot0): Add 'disable-pthreads'
phase.
* gnu/packages/patches/perl-no-sys-dirs.patch: Update.
* gnu/packages/patches/perl-module-pluggable-search.patch: Remove.
* gnu-system.am (dist_patch_DATA): Adjust accordingly.

gnu: gmp: Disable parallel tests.

* gnu/packages/multiprecision.scm (gmp)[arguments]: Disable parallel tests.

build: Add missing patches to the distribution.

* gnu-system.am (dist_patch_DATA): Add glibc-hurd-extern-inline.patch
and plink-1.07-unclobber-i.patch.

Merge branch 'master' into core-updates

gnu: numactl: Update to 2.0.11.

* gnu/packages/linux.scm (numactl)[source]: Update to 2.0.11.
  [native-inputs]: Drop autotools.
  [arguments]: Drop phase calling autogen.sh.

gnu: wget: Update to 1.17.1.

* gnu/packages/wget.scm (wget): Update to 1.17.1.

gnu: gcc: Use the system zlib.

* gnu/packages/gcc.scm (gcc-4.7) <configure-flags>: Pass
'--with-system-zlib'.
* gnu/packages/commencement.scm (gcc-boot0)[arguments]: Remove
'--with-system-zlib' from the configure flags.
* gnu/packages/commencement.scm (zlib-final): New variable.
(gcc-final)[arguments]: Add ZLIB-FINAL to #:allowed-references.
Pass -L and -Wl,-rpath for zlib in LDFLAGS, as a configure flag.
[inputs]: Add LD-WRAPPER-BOOT3 and ZLIB-FINAL.