Fix undefined-behavior in osquery::tables::genMemoryRegion
Fix undefined-behavior in osquery::tables::genMemoryRegion

Issue highlighted by asan activated in PR osquery/osquery#5628

Reading a 8 byte field from a 4 byte aligned struct needs to be
done with memcpy.

PR: osquery/osquery#5665

hackgnar/osquery,hackgnar/osquery,hackgnar/osquery