Remove unnecessary NoPointersBitmapPayload template.

[schveiguy]

Just noticed this, as I was trying to work on Associative Array fixes, and felt like this was worth a quick PR. Should save a few template instantiations.

[dlang-bot]

Thanks for your pull request, @schveiguy!

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[LightBender]

Is this possibly used by @rainers precise GC?

[schveiguy]

No, just the RTInfo is used. This template is only used to generate RTInfo, and it's only used to provide an enum to compare the pointer bitmap against.

Essentially, the RTInfo bitmap determines which word-sized chunks are pointers, and which aren't. The compiler provides the bitmaps, all this is doing is optimizing out cases where there are no pointers (to save on template instantiation).

Take a good look at the template, and see what it does. NoPointersBitmapPayload!N basically evaluates to size_t[N].init. I just replaced it to avoid the extra template.

Note: it's very likely this was tried, and didn't work back when it was added. I don't see why @kinke wouldn't have done that in the first place if it worked.