squashfs-tools aren't of much use without xz compression support
on OpenWrt, as we build kernel with squashfs supporting only xz.
Enabled support for xz compression by default.

Signed-off-by: Daniel Golle <daniel@makrotopia.org>

All patches are not needed anymore. squashfs-tools has implemented them in
one way or another.

Converted to download release tarballs. This should work better to get
notified of a newer release.

Also adds support for ZSTD compression:
  https://facebook.github.io/zstd/

Signed-off-by: Alexandru Ardelean <ardeleanalex@gmail.com>

Otherwise it will pull all compression libraries to install
(on newly configured targets) when maybe 1 or 2 are needed.

Signed-off-by: Alexandru Ardelean <ardeleanalex@gmail.com>

Picked up the old Makefile at 4.2.
Upgraded at 4.3 (repo move to github now: https://github.com/plougher/squashfs-tools/)
Added musl compatibility.
Enabled LZ4 compression support by default

Signed-off-by: Alexandru Ardelean <ardeleanalex@gmail.com>