[Issue 12768] Trivial uses of `std.algorithm.iteration : splitter` should be `@nogc`

[d-bugmail at puremagic.com]

https://issues.dlang.org/show_bug.cgi?id=12768

--- Comment #5 from Mathias LANG <pro.mathias.lang at gmail.com> ---
It's been 7 years, but I confirm it's still not `@nogc`:
```
import std.algorithm;

void main () @nogc
{
    auto rng = "Hello.Dear.World".splitter('.');
    assert(rng.front == "Hello"); // Error here
}
```

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