Fix Session cookie driver storing untrimmed user agent string in the database causing set_userdata() calls to fail when $config['sess_match_useragent'] = TRUE

Signed-off-by: Daniel Robbins <github@danieljrobbins.com>
Merge pull request #2295 from k3mist/fix-user-agent-match

Fix Session cookie driver storing untrimmed user agent string in the dat...
Fix #2298