Revert "Add mfence for signals too (consistency requirement)."
Revert "Add mfence for signals too (consistency requirement)."

This reverts commit 897f667d03e2c44de02c99b010df336e3560b23b.
We don't need this for consistency, we can simply mark things during decode.

s-kanev/XIOSim,s-kanev/XIOSim,s-kanev/XIOSim,s-kanev/XIOSim