virSecuritySELinuxTransactionCommit: Return -1 if no transaction is set
virSecuritySELinuxTransactionCommit: Return -1 if no transaction is set

Return -1 and report an error message if no transaction is set and
virSecuritySELinuxTransactionCommit is called.

The function description of virSecuritySELinuxTransactionCommit says:

  "Also it is considered as error if there's no transaction set and this
   function is called."

Signed-off-by: Marc Hartmayer <7bafc8cd4e6394916d396e4f8cde69753be8d066@linux.ibm.com>
Reviewed-by: Boris Fiuczynski <2648abdd55bfebf313fd324b464b047e6eea300e@linux.ibm.com>

olafhering/libvirt,crobinso/libvirt,crobinso/libvirt,crobinso/libvirt,andreabolognani/libvirt,jardasgit/libvirt,eskultety/libvirt,jfehlig/libvirt,jfehlig/libvirt,libvirt/libvirt,crobinso/libvirt,olafhering/libvirt,zippy2/libvirt,eskultety/libvirt,eskultety/libvirt,andreabolognani/libvirt,jfehlig/libvirt,nertpinx/libvirt,eskultety/libvirt,jardasgit/libvirt,nertpinx/libvirt,jfehlig/libvirt,olafhering/libvirt,jardasgit/libvirt,nertpinx/libvirt,andreabolognani/libvirt,libvirt/libvirt,jardasgit/libvirt,zippy2/libvirt,zippy2/libvirt,olafhering/libvirt,andreabolognani/libvirt,libvirt/libvirt,zippy2/libvirt,jardasgit/libvirt,libvirt/libvirt,fabianfreyer/libvirt,nertpinx/libvirt,nertpinx/libvirt,fabianfreyer/libvirt,eskultety/libvirt,fabianfreyer/libvirt,fabianfreyer/libvirt,fabianfreyer/libvirt,andreabolognani/libvirt