rustc_mir: do not treat NEEDS_DROP as unexpected in qualify_consts.
rustc_mir: do not treat NEEDS_DROP as unexpected in qualify_consts.

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