Log2 and beta test failures

[John W. Eaton]

On  6-May-2008, Jaroslav Hajek wrote:

| Found: The C99 standard, sec F.9.3.4 says specifically that f = frexp (x, &e)
| for x +inf or -inf should give f = x and e can be any value. This is
| consistent with my expectations: x = f * 2^e is an invariant of frexp.
| 
| I'd tend to regard this as a defect of MSVC, as there is probably no
| other standard to follow than C99. We should, however, at least fix
| the relevant test to not assume e = 0.
| 
| I'm not sure what is John's attitude about working around compiler
| incompatibilities like this;

A few fixes are probably OK, but I prefer to avoid littering Octave
code with workarounds for bugs in other software, especially when the
other software is freely available.

jwe