xz: Avoid printf formats like %2$s

xz: Avoid printf formats like %2$s

It's a POSIX feature that isn't in standard C. It's not available on
Windows. Even MinGW-w64 with __USE_MINGW_ANSI_STDIO doesn't support
it even though it supports POSIX %'d for thousand separators.

Gettext's <libintl.h> provides overrides for printf and other functions
which do support the %2$s formats. Translations use them. But xz should
work on Windows without <libintl.h> too.

Fixes: 3e9177fd206d20d6d8acc7d203c25a9ae0549229