Fix Issue 18932 - core.internal.hash.hashOf(val, seed) ignores seed when val is a raw pointer

[n8sh]

This PR makes this pass:

unittest
{
    import core.internal.hash : hashOf;
    assert(hashOf(null, 0) != hashOf(null, 123456789));
}

[dlang-bot]

Thanks for your pull request, @n8sh!

Bugzilla references

Auto-close	Bugzilla	Severity	Description
✓	18932	normal	core.internal.hash.hashOf(val, seed) ignores seed when val is a raw pointer

Testing this PR locally

If you don't have a local development environment setup, you can use Digger to test this PR:

dub fetch digger
dub run digger -- build "master + druntime#2202"

[wilzbach]

Once #2205 has been merged, CircleCi can be restarted and this PR can finally get merged.