Add tests for syscalls used for modifying the ownership of file

[aniketp]

Summary

The following revision introduces system calls from file-attribute-modify audit class
which deal with changing the ownership of a given file. System calls are:

• chown(2)
• fchown(2)
• lchown(2)
• fchownat(2)

Test Plan

Execute make && make install from test/sys/audit.
Execute kyua test from /usr/tests/sys/audit. All testcases should succeed.