includes/stg/SMP.h: implement simple load_/store_load_barrier on armv6 and older
Assuming there is no real SMP systems on these CPUs
I've added only compiler barrier (otherwise write_barrier
and friends need to be fixed as well).
Patch also fixes build breakage reported in Trac #10244.
Signed-off-by: Sergei Trofimovich <firstname.lastname@example.org>
Reviewers: rwbarton, nomeata, austin
Reviewed By: nomeata, austin
Subscribers: bgamari, thomie
Differential Revision: https://phabricator.haskell.org/D894
GHC Trac Issues: Trac #10244
(cherry picked from commit eaaa38ba24d5152623cb202a98f71ed09deef0bb)