databases/cego: update 2.31.1 -> 2.31.2

• Fix in CegoClient for escape character handling in batch mode
• Fix in CegoClient for dumpfile generation. Default values handling corrected
• Join optimizer fix in CegoSelect, CegoAttrCond and CegoBtreeCursor. join attributes are checked now in a more sophisticed way, which leads to improved execution performace for advanced joins

PR: Bjoern Lemke <lemke@lemke-it.com>