Remove $FreeBSD$: two-line .h pattern

Remove /^\s*\*\n \*\s+\$FreeBSD\$$\n/

Integrate tools/regression/lib/libc/net into the FreeBSD test suite
as lib/libc/tests/net

Also, fix eui64_aton_test:test_str(..). The test was comparing the result
of eui64_aton to a pointer of the expected result.

MFC after: 1 week
Sponsored by: EMC / Isilon Storage Division