[sqlite] Possible bug in SQLite in sqlite3VdbeSorterInit for PMA sorter size

[Andrew Cunningham]

I am using the option to set the main cache size

*PRAGMA **schema.**cache_size = -**kibibytes**;*

In function sqlite3VdbeSorterInit it seems that the calculation of mxCache
does not take into account the above alternate way to set cache_size that
uses the *-**kibibytes*  option.

....
....
     mxCache = db->aDb[0].pSchema->cache_size;
      if( mxCache<(int)szPma ) mxCache = (int)szPma;
      pSorter->mxPmaSize = MIN((i64)mxCache*pgsz, SQLITE_MAX_PMASZ);
....