[Issue 19346] std.math log* functions only have real versions

[d-bugmail at puremagic.com]

https://issues.dlang.org/show_bug.cgi?id=19346

--- Comment #2 from John Hall <john.michael.hall at gmail.com> ---
Not entirely, it seems the additions of `log1p` overloads for float and double
have messed with the accuracy of those functions (beyond what is to be expected
as a result of not doing intermediate calculations with reals). See:
https://issues.dlang.org/show_bug.cgi?id=23750

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