Log Message:
Disable db3 backend in GConf1:

  (1) The Berkeley DB storage backend requires DB-3.x, and used an
      experimental feature of DB-3.x.

  (2) There is a pretty severe bug that "prevents serious use of the
      Berkeley DB backend", according to the documentation included
      with the GConf sources.

  (3) GConf2, the successor to GConf, doesn't build with the Berkeley
      DB storage backend either.

Suggested by jlam.

Bump PKGREVISION.
Remove db3 bl3 inclusion from bl3 file, and bump BUILDLINK_DEPENDS
for it.

This fixes the gnucash build problems noted in PR 28423.