Merge remote-tracking branch 'remotes/cohuck/tags/s390x-20140425' into staging

Merge remote-tracking branch 'remotes/cohuck/tags/s390x-20140425' into staging

Some s390x patches:

- gdb stubs to make it compile if gdb support is pulled in
- linux-headers update for new oneregs
- two onereg enhancements

# gpg: Signature made Fri 25 Apr 2014 12:42:46 BST using RSA key ID C6F02FAF
# gpg: Can't check signature: public key not found

* remotes/cohuck/tags/s390x-20140425:
  s390x/kvm: sync gbea and pp register
  s390x/kvm: rework KVM synchronize to tracing for some ONEREGS
  linux-headers update
  s390x: empty function stubs in preparation for __KVM_HAVE_GUEST_DEBUG

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>