dev-lang/perl: Add := subslot deps for sys-libs/db

dev-lang/perl: Add := subslot deps for sys-libs/db

USE=berkdb compiles perl linking against sys-libs/db,
  indicating that removing the slot perl compiled against
  (which appears to be "latest") will cause Perl to be broken.

This change actually requires -r1 bumps for all dev-lang/perl
to propagate, however, that is a little too complex right now
in the tail of a stabilization.

Package-Manager: portage-2.3.1