[Issue 20200] Make std.math.isPowerOf2 work for floating point numbers in CTFE

[d-bugmail at puremagic.com]

https://issues.dlang.org/show_bug.cgi?id=20200
Issue 20200 depends on issue 20199, which changed state.

Issue 20199 Summary: Make std.math.frexp work in CTFE
https://issues.dlang.org/show_bug.cgi?id=20199

           What    |Removed                     |Added
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             Status|NEW                         |RESOLVED
         Resolution|---                         |FIXED

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