Big port infrastructure overhaul to ease module maintance. The user
visiable changes are:
- Use OPTIONS to control php#-mysql and pear-DB (for PostgreSQL
- Replace the DRUPDIR make variable with DRUPAL_BASE.
Other changes include abstracting some command paths and most of the
module makefiles out into a bsd.drupal.mk that lives in www/drupal for
now. Module updates to follow.