* gnu/packages/dbm.scm (bdb-4.8): New variable. [arguments]: Configure and build from 'build_unix' directory as mentioned in documentation. (bdb-5.3): Inherit from bdb-4.8. (bdb-6): Inherit from bdb-4.8. (bdb): Point to bdb-6.
* gnu/packages/dbm.scm (gdbm): Update to 1.18.1.
* gnu/packages/databases.scm (gdbm, bdb, bdb-5.3): Move from here... * gnu/packages/dbm.scm: ...to this new module. * gnu/local.mk (GNU_SYSTEM_MODULES): Add it. * gnu/packages/audio.scm, gnu/packages/avahi.scm, gnu/packages/backup.scm, gnu/packages/cobol.scm, gnu/packages/cyrus-sasl.scm, gnu/packages/databases.scm, gnu/packages/finance.scm, gnu/packages/game-development.scm, gnu/packages/gnome.scm, gnu/packages/guile.scm, gnu/packages/ibus.scm, gnu/packages/kerberos.scm, gnu/packages/linux.scm, gnu/packages/mail.scm, gnu/packages/man.scm, gnu/packages/nvi.scm, gnu/packages/openldap.scm, gnu/packages/package-management.scm, gnu/packages/php.scm, gnu/packages/pulseaudio.scm, gnu/packages/python.scm, gnu/packages/rdf.scm, gnu/packages/ruby.scm, gnu/packages/sawfish.scm: Update module references.
