systemc: Detect a process control corner case and report an error.
systemc: Detect a process control corner case and report an error.

This error reporting results in an exception being thrown, and one (or
more) of the tests depend on that behavior.

Change-Id: I858aa14fbb80b0648392179a6a8d2055c91aedf8
Reviewed-on: https://gem5-review.googlesource.com/12050
Reviewed-by: Gabe Black <5c8aa1266c03186393d9e7b3b4e3b14239af8201@google.com>
Maintainer: Gabe Black <5c8aa1266c03186393d9e7b3b4e3b14239af8201@google.com>

TUD-OS/gem5-dtu,TUD-OS/gem5-dtu,gem5/gem5,TUD-OS/gem5-dtu,TUD-OS/gem5-dtu,gem5/gem5,gem5/gem5,gem5/gem5,gem5/gem5,gem5/gem5,TUD-OS/gem5-dtu,TUD-OS/gem5-dtu,TUD-OS/gem5-dtu,gem5/gem5