Introduce memory failure events for hypervisor and guest. This lets
mft: Need exactly one file argument.  Try `mft --help' for more
information.

Suggested by Peter Maydell, rename events name&description to make
them architecture-neutral; and suggested by Paolo, add more info to
distinguish a mce is AR/AO, and if a previous MCE was still being
processed in the guest.

Signed-off-by: zhenwei pi <pizhenwei@bytedance.com>
Message-Id: <20200930100440.1060708-3-pizhenwei@bytedance.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>