EROFS File-System Adding DEFLATE Compression Support

While the EROFS Linux read-only file-system already supports LZ4 and microLZMA support, Zlib DEFLATE support is also being worked on and could be introduced in the next Linux kernel cycle.

EROFS developers have been working on DEFLATE compressed data support for this file-system. DEFLATE provides better compression ratios than the default LZ4 format but at the cost of higher CPU overhead. Initially this EROFS + DEFLATE support will be treated as an experimental feature.

Another benefit of adding DEFLATE support to EROFS is that a number of options exist for hardware acceleration of the algorithm such as with Intel IAA/QAT.

This commit in the EROFS.git "dev" branch lands the initial DEFLATE compression support. If all goes well it should in turn premiere with the Linux v6.6 kernel cycle.