Rollup merge of #144230 - RalfJung:option-as-slice-comment-fix, r=scottmcm

Option::as_slice: fix comment

The implementation got changed in rust-lang/rust#117525 without updating the comment. Now the comment makes no sense any more since there is no intrinsic that returns a pointer in this function any more.

(It is also very strange to say "in the new version" in a comment -- what is that supposed to tell someone reading the code 2 years later? That wording was introduced even earlier, in rust-lang/rust#109179.)

Cc `@GKFX` `@petrochenkov` `@llogiq` `@scottmcm`

Author: jhpratt