Previously, when passing the -re option while using multisim, the files
simerr.txt and simout.txt would be redirected into the m5out directory
instead of the correct subdirectory. They would also have a name of the
format
Spawn_gem5PoolWorker-some-integer_(simout|simerr).txt, which doesn't
indicate which simulation the files correspond to.
This commit fixes these issues by redirecting simerr.txt and simout.txt
into the correct subdirectory.
Change-Id: I0a25a9fd8dc672949f5f85fc5ca6452529301a73