Convert tools/regression/lib/libc/stdio/test-fpclassify into an ATF testcase and
Rename as lib/libc/stdio/fpclassify2_test

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Indent a couple lines properly and expand a comment.  No functional changes.
Skip the long-double epsilon checks on FreeBSD/i386

Sponsored by: EMC / Isilon Storage Division
Reset errno to 0 before running scalbn to be sure that the tested errno is
valid

Sponsored by: EMC / Isilon Storage Division
Alias isinff to isinf on FreeBSD

isinf on FreeBSD automatically picks the appropriate type per math.h

Sponsored by: EMC / Isilon Storage Division
- Expect exp2_powers to fail on FreeBSD/i386
- Expect exp2_values to fail on FreeBSD due to the small epsilon

Sponsored by: EMC / Isilon Storage Division