GCC bug 88127: qsort_r is not available in old glibc

[jpf91]

In GCC, we'll simply use the configure script to check if qsort_r is available and set Have_Qsort_R in gcc.config. Upstream druntime doesn't have an advanced build system which supports such checks, so just continue to assume the glibc supports qsort_r.

Can't use a version here, cause defining it with static if will lead to version defined after use errors.

Original bug report: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88127

ping @ibuclaw

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dub fetch digger
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[jpf91]

Thanks!

[ibuclaw]

I suspect that other platforms may require similar treatment depending on how far back we want to support things.

[jpf91]

Hmm, well I could wrap everything in a static if, if you prefer that?

// qsort_r may not be available
version (GNU)
    import gcc.config : Have_Qsort_R;
else
    enum Have_Qsort_R = true;

static if (Have_Qsort_R)
{
    version (CRuntime_Glibc)
    {
        enum Use_Qsort_R = true;
        ...
    }
    else version (FreeBSD)
    {
        enum Use_Qsort_R = true;
        ...
    }
    else version (DragonFlyBSD)
    {
        enum Use_Qsort_R = true;
        ...
    }
    else
    {
        enum Use_Qsort_R = false;
    }
}

static if (!Use_Qsort_R)
{
    //qsort implementation
}

However, I don't know how long qsort_r has been available on the other platforms.