remote: Don't call NULL closeFreeCallback
remote: Don't call NULL closeFreeCallback

Check function pointer before calling.

Signed-off-by: Viktor Mihajlovski <a96a137ca8976b5ff3114c85be7aeb3b6464dad7@linux.vnet.ibm.com>

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