Add PostgreSQL plugin to Windows

Added options:

  win: -plugin-sql-psql

Task-number: QTBUG-29802
Task-number: QTBUG-29974
Change-Id: Ic84772f343b0c86e522a924d4f356ea76b11166e
Reviewed-by: Iikka Eklund <iikka.eklund@digia.com>