first steps towards a QEMU target backend

- This commit only enables linking against QEMU.  The abstraction layer is
  completely dysfunctional at this time.
- QEMU's build system needs to be patched in order to create a static
  library.  This patch is currently not included in the Fail* repository.
- QEMU's JIT compilation may complicate or even preclude the implementation
  of some of Fail*'s backend abstractions.  Only a minimal subset (serial
  I/O, memory, memory writes, save/restore) is planned for the first phase.

git-svn-id: https://www4.informatik.uni-erlangen.de/i4svn/danceos/trunk/devel/fail@1615 8c4709b5-6ec9-48aa-a5cd-a96041d1645a