Fix tests most unused pattern variable warnings

[erickt]

I almost fixed all the unused variable warnings, and found a couple cases where we weren't properly using an enum because it wasn't imported. There were a couple I didn't know how to handle though:

/Users/etryzelaar/Projects/rust/rust/src/rustc/middle/ty.rs:1038:6: 1038:27 warning: unused variable: `sty`
/Users/etryzelaar/Projects/rust/rust/src/rustc/middle/ty.rs:1038       ref sty @ ty_fn(f) => {
                                                                       ^~~~~~~~~~~~~~~~~~~~~
/Users/etryzelaar/Projects/rust/rust/src/rustc/middle/ty.rs:2232:6: 2232:22 warning: unused variable: `re_bot`
/Users/etryzelaar/Projects/rust/rust/src/rustc/middle/ty.rs:2232       re_bot        => 4u
                                                                       ^~~~~~~~~~~~~~~~
/Users/etryzelaar/Projects/rust/rust/src/rustc/middle/typeck/check.rs:895:14: 895:43 warning: unused variable: `sty`
/Users/etryzelaar/Projects/rust/rust/src/rustc/middle/typeck/check.rs:895               sty @ ty::ty_fn(ref fn_ty) => {
                                                                                        ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~

I'm not quite sure what the sty @ ty::ty_fn(...) means, and re_bot seems like it should be a variant, but it doesn't exist.

[brson]

@nikomatsakis perhaps you can review this. Are we confident that none of these unused patterns indicate bugs?

[erickt]

By the way, I just rebased this onto HEAD to merge in the Some/None changes.

[nikomatsakis]

@brson I'll take a look.

[nikomatsakis]

@graydon this was one line that I was unsure about. It seemed like it could be a bug...? But prob not

[nikomatsakis]

I think it's pretty reasonable. There's only so many of those diffs you can look at until your eyes glaze over, but I didn't see anything that looked suspicious.

[brson]

This is merged.