[Issue 19048] In core.internal.hash.hashOf reduce template bloat: remove `auto ref` where unneeded and add `const` where possible

[d-bugmail at puremagic.com]

https://issues.dlang.org/show_bug.cgi?id=19048

Nathan S. <n8sh.secondary at hotmail.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
            Summary|In                          |In
                   |core.internal.hash.hashOf   |core.internal.hash.hashOf
                   |to reduce template bloat    |reduce template bloat:
                   |remove `auto ref` when it's |remove `auto ref` where
                   |not needed                  |unneeded and add `const`
                   |                            |where possible

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