debug/strace: 4.6 requires xz

strace 4.6 is only available as an XZ-compressed tarball.

Signed-off-by: "Yann E. MORIN" <yann.morin.1998@anciens.enib.fr>
(transplanted from d878322997095e513c6311ec3713b83ca91e5d8c)

reporter_name="Yann E. MORIN"

reporter_url="http://ymorin.is-a-geek.org/projects/crosstool"

reporter_comment="EXPERIMENTAL MIPS-64 n64 toolchain."