[Issue 21578] core.atomic.atomicFetchSub for pointers incorrectly calls wrong function from core.internal.atomic

[d-bugmail at puremagic.com]

https://issues.dlang.org/show_bug.cgi?id=21578

--- Comment #1 from ZombineDev <petar.p.kirov at gmail.com> ---
Test case:

import core.atomic;
shared(ulong)[] array = [2, 4, 6, 8, 10, 12, 14, 16, 19, 20];
{
    shared ulong* ptr = &array[0];
    shared(ulong)* prevPtr = atomicFetchAdd(ptr, 3); 
    assert(prevPtr == &array[0]); // OK
    assert(*prevPtr == 2); // OK
    assert(*ptr == 8); // OK
}
{
    shared ulong* ptr = &array[5];
    shared(ulong)* prevPtr = atomicFetchSub(ptr, 4); 
    assert(prevPtr == &array[5]); // OK
    assert(*prevPtr == 12); // OK
    assert(*ptr == 4); //fails
}

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