Restructured the gem5 backend:

- FailGem5Device is gone.
- There are now changes directly made to the gem5 source.
- Gem5Connector is a helper class that is compiled inside the gem5 context to workaround problems with gem5 header in fail.

Things that are working:
- BPSingleListener
- MemAccessListener
- Save and restore simulator state

git-svn-id: https://www4.informatik.uni-erlangen.de/i4svn/danceos/trunk/devel/fail@1820 8c4709b5-6ec9-48aa-a5cd-a96041d1645a