Extra RADIUS request attributes from SQLite

Extra RADIUS request attributes from SQLite

Add an SQLite table for defining per station MAC address version of
radius_auth_req_attr/radius_acct_req_attr information. Create the
necessary table and index where this doesn't exist. Select attributes
from the table keyed by station MAC address and request type (auth or
acct), parse and apply to a RADIUS message.

Add radius_req_attr_sqlite hostapd config option for SQLite database
file. Open/close RADIUS attribute database for a lifetime of a BSS and
invoke functions to add extra attributes during RADIUS auth and
accounting request generation.

Signed-off-by: Terry Burton <tez@terryburton.co.uk>