Work around a Linux arm32 unaligned data issue in SuperPMI (#56517)

Work around a Linux arm32 unaligned data issue in SuperPMI (#56517)

* Work around a Linux arm32 unaligned data issue in SuperPMI

impImportStaticReadOnlyField reads the data at the address returned by
getFieldAddress. SuperPMI saves and replays this data, but it doesn't
store it at a naturally aligned address. For int64/double (at least),
this is a problem on Linux arm32, which raises a SIGBUS exception on
such unaligned access.

This works around the problem by copying the potentially unaligned data
to a known aligned spot before reading it. This is only done under DEBUG
and when we know we are replaying under SuperPMI.

A proper fix would be to teach SuperPMI about alignment, but that would be
a large and risky change, compared to this small and isolated workaround.

The fixes the non-determinism of #56156.

* Only add alignment adjustment when required