Decrement reference to readResult in compressor iterator
Decrement reference to readResult in compressor iterator

This was causing a memory leak.
indygreg/python-zstandard,indygreg/python-zstandard,indygreg/python-zstandard,terrelln/python-zstandard,terrelln/python-zstandard,terrelln/python-zstandard,indygreg/python-zstandard,terrelln/python-zstandard