[core:db] fix syntax error with XOOPS_DB_PCONNECT=1

ref. http://xoopscube.jp/news/941
     http://usadeki.jp/modules/d3forum/index.php?topic_id=495
Merge branch 'legacy' into CorePack
[CorePack] CorePack version "CorePack 20130807"
Merge branch 'CorePack' into stable