Update to new upstream release 1.42.8.
Switch to KERNEL_ORG site and enable USE_XZ for 25 % smaller download.
Switch to USE_CSTD=gnu99 (was gnu89). Disable 2TB r_*_big_expand tests due
to their space requirements, reenable m_bigjournal, and also skip
f_extent_oobounds which breaks inside Tinderbox but is fine outside.