[PATCH 0/3] xen/mcelog: assorted adjustments

[Jan Beulich]

The 1st change is simple cleanup, noticed while preparing for the
2nd patch, which presents the consumer of the interface extension
proposed in
https://lists.xenproject.org/archives/html/xen-devel/2019-11/msg00377.html.
The 3rd patch is sort of optional, considering that 32-bit Xen
support is slated to be phased out of the kernel.

1: drop __MC_MSR_MCGCAP
2: add PPIN to record when available
3: also allow building for 32-bit kernels

Jan