systemc: Make verify.py compare non output log reference files.

systemc: Make verify.py compare non output log reference files.

There are only a few of these which are vcd files. If there are
reference files which aren't the log and which aren't in the gem5
output directory, mark those tests as failed as well.

Change-Id: I2c880c13d0f90ccf16ac0439dbac68de9223cc90
Reviewed-on: https://gem5-review.googlesource.com/12060
Reviewed-by: Gabe Black <gabeblack@google.com>
Maintainer: Gabe Black <gabeblack@google.com>