Remove some dead code.
Remove some dead code.

The condition checks if `sess.opts.output_types` doesn't contain
`OutputType::Assembly` within a match arm that is only reached if
`sess.opts.output_types` contains `OutputType::Assembly`.

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