decompressor: store total decompressed size in FrameSources
decompressor: store total decompressed size in FrameSources

To avoid extra computation in decompress_from_framepointers.
indygreg/python-zstandard,indygreg/python-zstandard,terrelln/python-zstandard,terrelln/python-zstandard,terrelln/python-zstandard,terrelln/python-zstandard,indygreg/python-zstandard,indygreg/python-zstandard