adding missing DB field

Can't upgrade a game if the field's missing so just add it. Adding a
notion of versioning and upgrading isn't worth the effort.

xwords4/linux/gamesdb.c

@@ -63,6 +63,7 @@ openGamesDB( const char* dbName )
         ",ntotal INT(2)"
         ",nmissing INT(2)"
         ",lastMoveTime INT"
+        ",dupTimerExpires INT"
         ")";
     result = sqlite3_exec( pDb, createGamesStr, NULL, NULL, NULL );