coredump: add DAX filtering for FDPIC ELF coredumps

coredump: add DAX filtering for FDPIC ELF coredumps

Orabug: 22913653

Add explicit filtering for DAX mappings to FDPIC ELF coredump.  This is
useful because DAX mappings have the potential to be very large.

This patch has only been compile tested.

Signed-off-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Acked-by: Jeff Moyer <jmoyer@redhat.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
(cherry picked from commit ab27a8d04b32b6ee8c30c14c4afd1058e8addc82)
Signed-off-by: Dan Duval <dan.duval@oracle.com>