Revert " some more xz improvements"

This reverts commit 79f00089f535e24efd65c958c8d57ce7b21f759e.

Conflicts:
	scripts/xz_wrap.sh
Revert "Fixed the xz compression and made it default"

This reverts commit 4e2b077bd73dcfbd0e726466f284fc58b037a8b4.