Removing header * man page of isinff

[coypu%sdf.org@localhost]

Hi,


In the next major bump we should get rid of the non-standard:
isnanf, isinff
(need to provide 'hidden' isnanf and provide a type-generic macro for
it per the standard)

Any objections for getting rid of the declaration of isinff and isnanf
in math.h, as well as getting rid of the man page?