selinux: Don't mask errors of virSecuritySELinuxGenNewContext
selinux: Don't mask errors of virSecuritySELinuxGenNewContext

Since cbe67ff9b0a5a94911afd4d12388bf182bcca86c
virSecuritySELinuxGenNewContext reports good error messages. Fix callers
that mask the errors by generic error message.

jfehlig/libvirt,VenkatDatta/libvirt,cbosdo/libvirt,jfehlig/libvirt,jfehlig/libvirt,shugaoye/libvirt,agx/libvirt,rlaager/libvirt,VenkatDatta/libvirt,jfehlig/libvirt,datto/libvirt,olafhering/libvirt,eskultety/libvirt,nertpinx/libvirt,jardasgit/libvirt,cbosdo/libvirt,zhlcindy/libvirt-1.1.4-maintain,zhlcindy/libvirt-1.1.4-maintain,zippy2/libvirt,rlaager/libvirt,zhlcindy/libvirt-1.1.4-maintain,nertpinx/libvirt,zhlcindy/libvirt-1.1.4-maintain,jardasgit/libvirt,datto/libvirt,rlaager/libvirt,zippy2/libvirt,elmarco/libvirt,shugaoye/libvirt,andreabolognani/libvirt,eskultety/libvirt,rlaager/libvirt,agx/libvirt,libvirt/libvirt,elmarco/libvirt,libvirt/libvirt,taget/libvirt,taget/libvirt,fabianfreyer/libvirt,datto/libvirt,nertpinx/libvirt,olafhering/libvirt,eskultety/libvirt,andreabolognani/libvirt,olafhering/libvirt,VenkatDatta/libvirt,crobinso/libvirt,eskultety/libvirt,jardasgit/libvirt,elmarco/libvirt,jardasgit/libvirt,olafhering/libvirt,libvirt/libvirt,cbosdo/libvirt,VenkatDatta/libvirt,nertpinx/libvirt,crobinso/libvirt,taget/libvirt,VenkatDatta/libvirt,fabianfreyer/libvirt,cbosdo/libvirt,nertpinx/libvirt,andreabolognani/libvirt,taget/libvirt,agx/libvirt,jardasgit/libvirt,fabianfreyer/libvirt,shugaoye/libvirt,fabianfreyer/libvirt,rlaager/libvirt,crobinso/libvirt,datto/libvirt,datto/libvirt,taget/libvirt,elmarco/libvirt,eskultety/libvirt,crobinso/libvirt,shugaoye/libvirt,zippy2/libvirt,elmarco/libvirt,libvirt/libvirt,fabianfreyer/libvirt,agx/libvirt,shugaoye/libvirt,agx/libvirt,cbosdo/libvirt,zhlcindy/libvirt-1.1.4-maintain,andreabolognani/libvirt,andreabolognani/libvirt,zippy2/libvirt