mysql: 5.7.X versions link boost (#11237)
mysql: 5.7.X versions link boost (#11237)

Fixes #11226

MySQL 5.7.X and Boost 1.59.0 have a closer relationship than
MySQL >= 8.0 and their corresponding Boost versions: 5.7.X needs to
link against boost libraries which is indicated by marking boost as
a link dependency (removing the 'type' reverts to the default, which
includes link and build).
LLNL/spack,iulian787/spack,LLNL/spack,LLNL/spack,iulian787/spack,iulian787/spack,LLNL/spack,iulian787/spack,iulian787/spack,LLNL/spack