Add support for the postgresql database

Packages describing “postgres” as local USE flag

Package“postgres” Flag Description
app-admin/rsyslogBuild the PostgreSQL database output module (requires dev-db/postgresql)
app-mobilephone/gammuUse PostgreSQL for data storage
net-analyzer/check_mk_agentInstall check_mk-agent postgres plugin.
net-analyzer/muninInstall the packages required for monitoring PostgreSQL. Disabling the flag does not remove any plugin files.
net-im/ejabberdEnable PostgreSQL support for data storage
net-irc/inspircdEnable PostgreSQL database backend
net-voip/yateuse Postgress SQL

All packages providing a “postgres” USE flag (133)