groff: build less in groff-native

groff: build less in groff-native

When building groff-native we only really need enough of groff to build
manpages, and don't need documentation or extra tools.

Patch the Makefile to stop building the doc and contrib directories,
which both take time and have incomplete build dependencies that cause
intermittent failures[1][2].

This makes groff-native faster to build:

  groff-native    do_compile   -30.6s   -33.7%     90.9s -> 60.3s

And some tools are removed, which I don't believe are needed by anything
we build:

  /usr/bin/chem was removed
  /usr/bin/eqn2graph was removed
  /usr/bin/gdiffmk was removed
  /usr/bin/gperl was removed
  /usr/bin/gpinyin was removed
  /usr/bin/mmroff was removed
  /usr/bin/pic2graph was removed
  /usr/share/groff/1.24.1/tmac/chem.pic was removed
  /usr/share/groff/1.24.1/tmac/hdmisc.tmac was removed
  /usr/share/groff/1.24.1/tmac/hdtbl.tmac was removed
  /usr/share/groff/1.24.1/tmac/mm was removed
  /usr/share/groff/1.24.1/tmac/mm/0.MT was removed
  /usr/share/groff/1.24.1/tmac/mm/4.MT was removed
  /usr/share/groff/1.24.1/tmac/mm/5.MT was removed
  /usr/share/groff/1.24.1/tmac/mm/ms.cov was removed
  /usr/share/groff/1.24.1/tmac/mm/se_ms.cov was removed
  /usr/share/groff/1.24.1/tmac/mmse.tmac was removed
  /usr/share/groff/1.24.1/tmac/mm.tmac was removed
  /usr/share/groff/1.24.1/tmac/mom.tmac was removed
  /usr/share/groff/1.24.1/tmac/mse.tmac was removed
  /usr/share/groff/1.24.1/tmac/m.tmac was removed
  /usr/share/groff/1.24.1/tmac/om.tmac was removed
  /usr/share/groff/1.24.1/tmac/refer-mm.tmac was removed
  /usr/share/groff/1.24.1/tmac/rfc1345.tmac was removed
  /usr/share/groff/1.24.1/tmac/sboxes.tmac was removed

[1] oe-core d1a02bdd242 ("groff: Fix occasional build race failure")
[2] https://bugzilla.yoctoproject.org/show_bug.cgi?id=16279

Signed-off-by: Ross Burton <ross.burton@arm.com>
Signed-off-by: Antonin Godard <antonin.godard@bootlin.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>