https://github.com/tukaani-project/xz

Fixes: xz#6

... as the github one is locked.

https://tukaani.org/xz-backdoor/

improve reproducibility by running autogen.sh ourselves

devtools 20230105-1 enables the debug option by default.

A follow-up commit will remove debug from alongside other options.

archlinux/devtools!109 (comment 74475)

lib32-gcc-libs is in multilib-devel which is what is needed, now that core/gcc
has native -m32 support.

Also clean up misc issues e.g. unquoted srcdir/pkgdir encountered along the way