CrayPrgEnv:
  - add a new function __cmake_craype_linktype() that determines what
    link mode the Cray compiler wrapper will use in a more sophisticated
    way than just MATCHing for static/dynamic on the command line.

  - add a new function __cmake_craype_setupenv() that does a
    once-per-cmake-run setup that does the following:
       1. does a basic check of the wrapper's configuration.  Running
          cmake and then changing module and/or linktype configuration
          may cause build problems (since the data in the cmake cache
          may no longer be correct after the change).  We look for this
          and warn the user about it.
       2. uses the "module" provided PKG_CONFIG_PATH environment variable
          to add additional prefixes to the system prefix path.  This
          function used to be done by CrayLinuxEnvironment using the
          compiler implicit include/link paths but that is intended
          only for cr...