Drop mntent.h include.
Drop mntent.h include.

It's no longer used and also causes build fail on FreeBSD.

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