The upstream kernel has dropped it because real 32-bit hardware almost
never has RAM > 4 GiB. The users running 32-bit software on 64-bit
hardware should really switch to MLFS now.
Regenerating the XML files also makes the prompt for X2APIC consistent
with the 6.15 kernel.
Import kernel-config infrastructure from BLFS and use it for kernel
configuration. Note that kernel-config.py is slightly different from
BLFS: we need role="nodump" for <screen> here.
