Preparation for make installcheck

1. Install pg_dbms_stats into the target binary tree. Make sure to
   prepare the PATH environment variable properly to execute the right
   pg_config for the version of target PostgreSQL server.

  postgres$ which pg_config
  <somewhere bin of the target server resides>/pg_config
  postgres$ make install

2. Install additionally required contrib module file_fdw. This could
  be done for RPM installed server by installing postgresql##-contrib
  using yum after installing additional repository.

  # yum install postgresql96-contrib

3. Edit postgresql.conf so that pg_dbms stats will be automatically
   loaded.

  postgres$ echo "shared_preload_libraries = 'pg_dbms_stats'" >>  <PGDATA>/postgresql.conf

4. Start the target server

  postgres$ postgres or pg_ctl start

5. Install extension on the server.

  postgres$ psql postgres -c 'CREATE EXTENSION pg_dbms_stats; CREATE EXTENSION file_fdw;'

6. run make installcheck

  postgres$ make installcheck