zlib: handle Z_BUF_ERROR properly

A Z_BUF_ERROR can occur when all input has been consumed, but could not
produce any additional output.  It is not possible to always know
whether more output can be produced without additional input, so such
"errors" are unavoidable, but harmless.  See
http://zlib.net/zlib_how.html for more information.

Signed-off-by: Evan Nemerson <evan@coeus-group.com>
blosc: set default number of threads when using options

Signed-off-by: Evan Nemerson <evan@coeus-group.com>
blosc: do not allow compression level 0 (no compression)

Signed-off-by: Evan Nemerson <evan@coeus-group.com>
wflz: fix compile-time disabling

Signed-off-by: Evan Nemerson <evan@coeus-group.com>
lzo: allow choosing compression level

Signed-off-by: Evan Nemerson <evan@coeus-group.com>
lzma: avoid re-using LZMA options structure when sharing Squash options

Signed-off-by: Evan Nemerson <evan@coeus-group.com>
Whitespace fixes.

Signed-off-by: Evan Nemerson <evan@coeus-group.com>
wflz: add wflz-chunked codec.

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