Attempt to mmap the input and output when compressing streams.
Attempt to mmap the input and output when compressing streams.

This short circuits the whole SquashBufferStream hack when possible,
which can be a huge performance boost (50-100% for several codecs).

Signed-off-by: Evan Nemerson <178b62e73cc3fab9e30bf27b2372c9ff92401915@coeus-group.com>

quixdb/squash,Cloudef/squash,Cloudef/squash,wolut/squash,jibsen/squash,quixdb/squash,wolut/squash,jibsen/squash,jibsen/squash,wolut/squash,Cloudef/squash,quixdb/squash