threadpool: allow NULL jobdata
threadpool: allow NULL jobdata

Don't require non-null jobdata to virThreadPoolSendJob().

jardasgit/libvirt,rlaager/libvirt,trainstack/libvirt,datto/libvirt,taget/libvirt,elmarco/libvirt,agx/libvirt,nertpinx/libvirt,rmarwaha/libvirt,kantai/libvirt-vfork,fabianfreyer/libvirt,novel/fbsd-libvirt,wiedi/libvirt,novel/fbsd-libvirt,cbosdo/libvirt,wiedi/libvirt,andreabolognani/libvirt,emaste/libvirt,taget/libvirt,jeckersb/libvirt,wiedi/libvirt,foomango/libvirt,elmarco/libvirt,andreabolognani/libvirt,jeckersb/libvirt,libvirt/libvirt,rmarwaha/libvirt1,novel/fbsd-libvirt,olafhering/libvirt,foomango/libvirt,jeckersb/libvirt,zhlcindy/libvirt-1.1.4-maintain,leilihh/libvirt,emaste/libvirt,emaste/libvirt,VenkatDatta/libvirt,foomango/libvirt,soulxu/libvirt-xuhj,cbosdo/libvirt,rlaager/libvirt,nertpinx/libvirt,trainstack/libvirt,shugaoye/libvirt,rbu/libvirt,bjzhang/libvirt,warewolf/libvirt,jfehlig/libvirt,warewolf/libvirt,rmarwaha/libvirt,olafhering/libvirt,eskultety/libvirt,eskultety/libvirt,wiedi/libvirt,sshah-solarflare/Libvirt-PCI-passthrough-,eskultety/libvirt,crobinso/libvirt,leilihh/libvirt,trainstack/libvirt,danwent/libvirt-ovs,danwent/libvirt-ovs,wiedi/libvirt,kantai/libvirt-vfork,warewolf/libvirt,elmarco/libvirt,rlaager/libvirt,datto/libvirt,bjzhang/libvirt,rmarwaha/libvirt1,siboulet/libvirt-openvz,emaste/libvirt,danwent/libvirt-ovs,iam-TJ/libvirt,sshah-solarflare/Libvirt-PCI-passthrough-,soulxu/libvirt-xuhj,foomango/libvirt,leilihh/libvirt,rmarwaha/libvirt,soulxu/libvirt-xuhj,zhlcindy/libvirt-1.1.4-maintain,kantai/libvirt-vfork,VenkatDatta/libvirt,siboulet/libvirt-openvz,nertpinx/libvirt,olafhering/libvirt,emaste/libvirt,rmarwaha/libvirt1,VenkatDatta/libvirt,zippy2/libvirt,siboulet/libvirt-openvz,rbu/libvirt,iam-TJ/libvirt,warewolf/libvirt,rbu/libvirt,zippy2/libvirt,agx/libvirt,trainstack/libvirt,agx/libvirt,danwent/libvirt-ovs,usc-isi/libvirt,soulxu/libvirt-xuhj,cbosdo/libvirt,libvirt/libvirt,jfehlig/libvirt,fabianfreyer/libvirt,zippy2/libvirt,warewolf/libvirt,eskultety/libvirt,andreabolognani/libvirt,jeckersb/libvirt,libvirt/libvirt,leilihh/libvirt,warewolf/libvirt,andreabolognani/libvirt,fabianfreyer/libvirt,crobinso/libvirt,novel/fbsd-libvirt,zhlcindy/libvirt-1.1.4-maintain,iam-TJ/libvirt,rbu/libvirt,usc-isi/libvirt,novel/fbsd-libvirt,novel/fbsd-libvirt,VenkatDatta/libvirt,jeckersb/libvirt,zhlcindy/libvirt-1.1.4-maintain,usc-isi/libvirt,dumbbell/libvirt,bjzhang/libvirt,rmarwaha/libvirt,nertpinx/libvirt,soulxu/libvirt-xuhj,novel/fbsd-libvirt,crobinso/libvirt,shugaoye/libvirt,taget/libvirt,dumbbell/libvirt,fabianfreyer/libvirt,novel/fbsd-libvirt,jfehlig/libvirt,nertpinx/libvirt,leilihh/libvirt,cbosdo/libvirt,olafhering/libvirt,usc-isi/libvirt,jardasgit/libvirt,dumbbell/libvirt,wiedi/libvirt,jardasgit/libvirt,dumbbell/libvirt,libvirt/libvirt,eskultety/libvirt,shugaoye/libvirt,taget/libvirt,siboulet/libvirt-openvz,elmarco/libvirt,bjzhang/libvirt,jeckersb/libvirt,trainstack/libvirt,emaste/libvirt,elmarco/libvirt,dumbbell/libvirt,kantai/libvirt-vfork,jeckersb/libvirt,rmarwaha/libvirt1,rmarwaha/libvirt1,usc-isi/libvirt,rlaager/libvirt,rbu/libvirt,bjzhang/libvirt,iam-TJ/libvirt,danwent/libvirt-ovs,sshah-solarflare/Libvirt-PCI-passthrough-,shugaoye/libvirt,rmarwaha/libvirt1,zippy2/libvirt,novel/fbsd-libvirt,agx/libvirt,jfehlig/libvirt,sshah-solarflare/Libvirt-PCI-passthrough-,dumbbell/libvirt,jardasgit/libvirt,datto/libvirt,rlaager/libvirt,agx/libvirt,fabianfreyer/libvirt,siboulet/libvirt-openvz,taget/libvirt,warewolf/libvirt,kantai/libvirt-vfork,zhlcindy/libvirt-1.1.4-maintain,crobinso/libvirt,leilihh/libvirt,cbosdo/libvirt,andreabolognani/libvirt,emaste/libvirt,rmarwaha/libvirt,iam-TJ/libvirt,sshah-solarflare/Libvirt-PCI-passthrough-,trainstack/libvirt,wiedi/libvirt,trainstack/libvirt,foomango/libvirt,iam-TJ/libvirt,iam-TJ/libvirt,datto/libvirt,jardasgit/libvirt,rmarwaha/libvirt,shugaoye/libvirt,datto/libvirt,VenkatDatta/libvirt