Fix unveil for relative lookups in the non AT_FDCWD case

Issue spotted by Benjamin Baier <programmer@netzbasis.de> with relative
path lookups from openat(2). Lacking a current working directory unveil,
operations using the *at functions could fail when not crossing an unveil,
since an initial covering unveil was not found.

This corrects this so we walk up from the directory vnode to find a
covering unveil at the start of non AT_FDCWD lookups, and adds regress
for this case.

ok bluhm@

0 files changed, 0 insertions, 0 deletions