rustc: Move a comment to the right spot in trans
rustc: Move a comment to the right spot in trans

I believe this comment here is mostly talking about the `ptrcast` function call
below, so move the comment down to that block.

graydon/rust,GBGamer/rust,GBGamer/rust,GBGamer/rust,aidancully/rust,graydon/rust,GBGamer/rust,graydon/rust,graydon/rust,aidancully/rust,aidancully/rust,aidancully/rust,GBGamer/rust,aidancully/rust,graydon/rust,GBGamer/rust,graydon/rust,aidancully/rust,GBGamer/rust,GBGamer/rust