virnetttlcontext: Resolve issues found by Valgrind
virnetttlcontext: Resolve issues found by Valgrind

Need to initialize 'usage' and 'critical' since the VIR_DEBUG will
attempt to use them.

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