Fix error reporting in virSecuritySELinuxGenNewContext
Fix error reporting in virSecuritySELinuxGenNewContext

The virSecuritySELinuxGenNewContext method was not reporting any
errors, leaving it up to the caller to report a generic error.
In addition it could potentially trigger a strdup(NULL) in an
OOM scenario. Move all error reporting into the
virSecuritySELinuxGenNewContext method where accurate info
can be provided

Signed-off-by: Daniel P. Berrange <bb938cf255e055ff3507f2627d214e8e62118fcf@redhat.com>

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