Remove $FreeBSD$: two-line .h pattern

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

Convert the msun tests to ATF

This provides better error messages that just an assertion failure and
also makes it easier to mark individual tests as XFAIL.
It was also helpful when coming up with D28786 and D28787.

Differential Revision: https://reviews.freebsd.org/D28798

Integrate a number of testcases from tools/regression/lib/msun
into the FreeBSD test suite

There's no functional change with these testcases; they're purposely
being left in TAP format for the time being

Other testcases which crash on amd64/i386 as-is have not been
integrated yet (they need to be retested on a later version of
CURRENT, as I haven't used i386 in some time)

MFC after: 3 weeks
Sponsored by: EMC / Isilon Storage Division