tools/squashfs4: update to 4.7.0

tools/squashfs4: update to 4.7.0

This new version introduced parallel file reading, which will
greatly improve the IO performance. OpenWrt only uses GZIP
and XZ compression, hence the LZ4, LZO and ZSTD compression
algorithms were explicitly disabled.

Upstreamed patches:
  001-xz_wrapper-support-multiple-lzma-configuration-optio.patch[1]
  002-xz_wrapper-make-new-OpenWrt-extended-options-non-def.patch[2]

Release Notes:
https://github.com/plougher/squashfs-tools/releases/tag/4.7

[1] https://github.com/plougher/squashfs-tools/commit/dcb976fe4ee40e4bac8ae0dcc836629c625a6fd4
[2] https://github.com/plougher/squashfs-tools/commit/5fb9fdfb8757fc9afb6318a3dcf9dce0a97de352

Signed-off-by: Shiji Yang <yangshiji66@outlook.com>
Link: https://github.com/openwrt/openwrt/pull/19019
Signed-off-by: Nick Hainke <vincent@systemli.org>