virDomainFormatSchedDef: Avoid false positive NULL dereference
virDomainFormatSchedDef: Avoid false positive NULL dereference

Okay, I admit that our code here is complex. It's not easy to
spot that NULL deref can't really happen here. So it's no wonder
that a dumb compiler fails to see all the connections and
produces the following errors:

  CC       conf/libvirt_conf_la-domain_conf.lo
conf/domain_conf.c: In function 'virDomainDefFormatInternal':
conf/domain_conf.c:22162:22: error: potential null pointer dereference [-Werror=null-dereference]
             if (sched->policy == i)
                 ~~~~~^~~~~~~~
<snip/>
cc1: all warnings being treated as errors

Signed-off-by: Michal Privoznik <83d82aaba2eed257f4814b0c239c260c4caaadf0@redhat.com>

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