configure: Use ustar format for dist tarball
configure: Use ustar format for dist tarball

Since for stable releases, some test files were over the 99 char
limit for traditional tar filenames.

Suggested by Osier here:
https://www.redhat.com/archives/libvir-list/2012-April/msg01435.html

Signed-off-by: Cole Robinson <7cd45ff6ad1fb7cf556a02797d774247851499f8@redhat.com>

siboulet/libvirt-openvz,libvirt/libvirt,datto/libvirt,siboulet/libvirt-openvz,siboulet/libvirt-openvz,libvirt/libvirt,trainstack/libvirt,agx/libvirt,warewolf/libvirt,datto/libvirt,bjzhang/libvirt,novel/fbsd-libvirt,fabianfreyer/libvirt,andreabolognani/libvirt,agx/libvirt,bjzhang/libvirt,nertpinx/libvirt,jardasgit/libvirt,libvirt/libvirt,elmarco/libvirt,bjzhang/libvirt,rmarwaha/libvirt,andreabolognani/libvirt,jfehlig/libvirt,fabianfreyer/libvirt,cbosdo/libvirt,eskultety/libvirt,taget/libvirt,trainstack/libvirt,taget/libvirt,jfehlig/libvirt,shugaoye/libvirt,jardasgit/libvirt,novel/fbsd-libvirt,emaste/libvirt,olafhering/libvirt,wiedi/libvirt,novel/fbsd-libvirt,cbosdo/libvirt,wiedi/libvirt,trainstack/libvirt,wiedi/libvirt,jardasgit/libvirt,eskultety/libvirt,emaste/libvirt,emaste/libvirt,nertpinx/libvirt,agx/libvirt,novel/fbsd-libvirt,iam-TJ/libvirt,zhlcindy/libvirt-1.1.4-maintain,shugaoye/libvirt,iam-TJ/libvirt,novel/fbsd-libvirt,datto/libvirt,wiedi/libvirt,rmarwaha/libvirt1,elmarco/libvirt,rlaager/libvirt,rlaager/libvirt,olafhering/libvirt,iam-TJ/libvirt,shugaoye/libvirt,bjzhang/libvirt,fabianfreyer/libvirt,emaste/libvirt,andreabolognani/libvirt,shugaoye/libvirt,trainstack/libvirt,zhlcindy/libvirt-1.1.4-maintain,cbosdo/libvirt,rlaager/libvirt,novel/fbsd-libvirt,VenkatDatta/libvirt,siboulet/libvirt-openvz,wiedi/libvirt,zippy2/libvirt,trainstack/libvirt,rmarwaha/libvirt,zhlcindy/libvirt-1.1.4-maintain,iam-TJ/libvirt,jeckersb/libvirt,rmarwaha/libvirt,rmarwaha/libvirt1,jardasgit/libvirt,eskultety/libvirt,nertpinx/libvirt,elmarco/libvirt,zippy2/libvirt,taget/libvirt,shugaoye/libvirt,rmarwaha/libvirt1,warewolf/libvirt,warewolf/libvirt,siboulet/libvirt-openvz,elmarco/libvirt,warewolf/libvirt,emaste/libvirt,iam-TJ/libvirt,VenkatDatta/libvirt,emaste/libvirt,novel/fbsd-libvirt,datto/libvirt,jfehlig/libvirt,wiedi/libvirt,warewolf/libvirt,andreabolognani/libvirt,jfehlig/libvirt,dumbbell/libvirt,eskultety/libvirt,andreabolognani/libvirt,dumbbell/libvirt,jeckersb/libvirt,rmarwaha/libvirt,trainstack/libvirt,fabianfreyer/libvirt,jardasgit/libvirt,dumbbell/libvirt,nertpinx/libvirt,VenkatDatta/libvirt,libvirt/libvirt,jeckersb/libvirt,agx/libvirt,novel/fbsd-libvirt,VenkatDatta/libvirt,zippy2/libvirt,rmarwaha/libvirt1,elmarco/libvirt,jeckersb/libvirt,rmarwaha/libvirt1,cbosdo/libvirt,bjzhang/libvirt,datto/libvirt,nertpinx/libvirt,emaste/libvirt,rmarwaha/libvirt1,zhlcindy/libvirt-1.1.4-maintain,zhlcindy/libvirt-1.1.4-maintain,taget/libvirt,agx/libvirt,eskultety/libvirt,rlaager/libvirt,jeckersb/libvirt,iam-TJ/libvirt,jeckersb/libvirt,trainstack/libvirt,olafhering/libvirt,zippy2/libvirt,taget/libvirt,rlaager/libvirt,dumbbell/libvirt,cbosdo/libvirt,crobinso/libvirt,rmarwaha/libvirt,wiedi/libvirt,warewolf/libvirt,crobinso/libvirt,dumbbell/libvirt,warewolf/libvirt,dumbbell/libvirt,crobinso/libvirt,jeckersb/libvirt,fabianfreyer/libvirt,novel/fbsd-libvirt,olafhering/libvirt,rmarwaha/libvirt,crobinso/libvirt,VenkatDatta/libvirt,iam-TJ/libvirt