On a live system during session initialization, delay the first read
error message (typically when reading the "cpu_possible_mask") until
it is confirmed that all of the following are true:
  (1) /dev/crash does not exist, and
  (2) /dev/mem is restricted via CONFIG_STRICT_DEVMEM, and
  (3) /proc/kcore cannot be read/accessed.
The "kernel may be configured with CONFIG_STRICT_DEVMEM" and
the "trying /proc/kcore as an alternative" messages will still
be displayed when appropriate.  The read error message be displayed
only if all three live memory read options fail.
(anderson@redhat.com)