Log Message:
Use the omf.mk file provided by the scrollkeeper package to automatically
rebuild the documentation database at install/deinstall time. This means
that:
- PLIST's do not need to call scrollkeeper-{update,rebuilddb} directly;
  this is done by a bsd.pkg.install.mk template.
- The share/omf directory is only removed by scrollkeeper, which is the
  last package in the dependancy tree.
- PKGREVISION is bumped.

Reviewed by wiz.