ovl: remove privs in ovl_fallocate()
JIRA: https://issues.redhat.com/browse/RHEL-17368
Testing: The generic/68[3-7] test cases still fail, but only because SGID without group execute is not cleared. SUID is cleared unconditionally and SGID + group execute is also cleared. The full fix involves VFS changes and is difficult to backport
Signed-off-by: Miklos Szeredi mszeredi@redhat.com