Some small optimization in connection.cpp

Some small optimization in makeSplitPacket func. If we know data.getSize() and maximum_data_size we can calulate number of chunks. For example: size = 1105, max = 495. The number = (int)(size/max)+1=3 (2*495 + 115) where 115 - tail of data block. And we can write chunks_count in the first cycle.

After this optimisation we have 1 cycle and calc some variables around cycle.