Master broken trying to use `seek_after` function

[MrAwesome]

When trying to build clippy off of a clean master, I get the following failure:

error[E0624]: associated function `seek_after` is private
   --> clippy_lints/src/redundant_clone.rs:594:25
    |                  
594 |         self.maybe_live.seek_after(at);
    |                         ^^^^^^^^^^ private associated function
                                  
error: aborting due to previous error

I poked around in rustc_mir and guess that this is the culprit - the timing matches up with when I started seeing breakages locally while testing: rust-lang/rust@65b4482

It looks like changing this to seek_after_primary_effect fixes the build - I'll put up a PR to do that.

[MrAwesome]

Looks like this is already being addressed in #5566.