util: guarantee sane errno in virFileIsExecutable
util: guarantee sane errno in virFileIsExecutable

If virFileIsExecutable is to replace access(file,X_OK), then
errno must be usable on failure.

* src/util/util.c (virFileIsExecutable): Set errno on failure.

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