arch,cpu: Refactor PCState construction a little.

Make the Addr constructor explicit to avoid implicit/hidden conversions
from Addr.

Also, add a copy constructor to the PCState types, and explicitly enable
the assignment operator.

Change-Id: Ibef17ece7fd06b2f9709c46d118e88a80da0b194
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/52036
Tested-by: kokoro <noreply+kokoro@google.com>
Reviewed-by: Daniel Carvalho <odanrc@yahoo.com.br>
Maintainer: Bobby R. Bruce <bbruce@ucdavis.edu>
13 files changed