Fix compatibility with Boost 1.67+

[mcs07]

Boost 1.67+ uses a version suffix like "python36" or "python27" for the boost python library. This updates CMakeLists.txt to look for this (in addition to the existing lookups).

See: https://github.com/Kitware/CMake/blob/master/Modules/FindBoost.cmake#L43-L50 and also https://github.com/Kitware/CMake/blob/master/Modules/FindBoost.cmake#L202-L207 for more info.

Tested with boost 1.67 from conda-forge on windows, but this should hopefully also fix homebrew boost 1.67 on Mac - see rdkit/homebrew-rdkit#62.

[greglandrum]

Thanks Matt.

[UnixJunkie]

I think there is a similar problem with boost-1.71

CMake Error at /usr/local/lib/cmake/Boost-1.71.0/BoostConfig.cmake:117 (find_package):
  Could not find a package configuration file provided by "boost_python"
  (requested version 1.71.0) with any of the following names:

    boost_pythonConfig.cmake
    boost_python-config.cmake

  Add the installation prefix of "boost_python" to CMAKE_PREFIX_PATH or set
  "boost_python_DIR" to a directory containing one of the above files.  If
  "boost_python" provides a separate development package or SDK, be sure it
  has been installed.
Call Stack (most recent call first):
  /usr/local/lib/cmake/Boost-1.71.0/BoostConfig.cmake:182 (boost_find_component)
  /usr/local/Cellar/cmake/3.15.3/share/cmake/Modules/FindBoost.cmake:443 (find_package)
  CMakeLists.txt:262 (find_package)

[UnixJunkie]

@mcs07 can you compile rdkit with boost-1.71? I don't manage to fix this.