increased nbAttempts for lz4 -12
increased nbAttempts for lz4 -12

shaves one more kilobyte from silesia.tar

unknownbrackets/maxcso,unknownbrackets/maxcso,unknownbrackets/maxcso,unknownbrackets/maxcso,unknownbrackets/maxcso,unknownbrackets/maxcso,unknownbrackets/maxcso