devel/llvm38 & custom poudriere

[Christian Schwarz]

> I tried fiddling around by symlinkng /usr/bin/cc to the clang binaries,
> this was not successful however.

Apparently, I was not symlinking correctly. The way I got my 
drm-next-4.7 poudriere jail running:

  zfs create zroot/poudriere/jails/12graphics
  zfs set mountpoint=/usr/local/poudriere/jails/12graphics zroot/poudriere/jails/12graphics
  # manually create the poudriere.d/jail/12graphics
  #   by copying & adjusting a regular build jail
  cd path-to-drm-next-4.7
  make buildworld
  make installworld DESTDIR=/usr/local/poudriere/jails/12graphics
  make distribution DESTDIR=/usr/local/poudriere/jails/12graphics
  zfs snapshot zroot/poudriere/jails/12graphics at nollvm
  cp /etc/resolv.conf /usr/local/poudriere/jails/12graphics/etc/resolv.conf
  pkg --chroot /usr/local/poudriere/jails/12graphics install clang38
  rm /etc/resolv.conf
  echo 'CC=/usr/local/bin/clang38' >> /usr/local/etc/poudriere.d/12graphics-make.conf
  echo 'CXX=/usr/local/bin/clang++38' >> /usr/local/etc/poudriere.d/12graphics-make.conf
  echo 'CPP=/usr/local/bin/clang-cpp38' >> /usr/local/etc/poudriere.d/12graphics-make.conf
  # symlink c** binaries for ./configure scripts 
  cd /usr/local/poudriere/jails/12graphics/usr/bin
  ln -s ../local/llvm/bin/clang cc
  ln -s ../local/llvm/bin/clang++ c++
  ln -s ../local/llvm/bin/clang-cpp cpp
  # create the zfs snapshot @clean, it is used as source for build jail clones created by poudriere
  zfs snapshot zroot/poudriere/jails/12graphics at clean
  poudriere bulk -j 12graphics -p xserver-next -c -f /usr/local/etc/poudriere.d/myports.list

Notic the make.conf in the jail is no longer used, instead, we use the
poudriere feature.

Hope this is useful to someone,

Christian