fix #17952 - Invalid printf checks for long double on windows

[rainers]

The MS runtime doesn't support real if it is larger than double.

Is there a better option for portable code than to always use cast(c_long_double) for reals?

FYI: @denizzzka

[rainers]

LDC will probably have to tweak the tests a bit, because it has real == double. There is no condition "windows but not LDC" for text replacement, though.

[denizzzka]

Paranoidal: maybe identity of real and double types would be better to check as:

version(Windows)
{
       bool isRealIdenticalToDouble = (
            real.mant_dig == double.mant_dig
            && real.min_exp == double.min_exp
            && real.max_exp == double.max_exp
        )
}

?

[rainers]

Paranoidal: maybe identity of real and double types would be better to check as:

That would test the host compiler, not the target to build for. The current target information is not that detailed.