Run rustfmt on tests/codegen/.

Except for `simd-intrinsic/`, which has a lot of files containing
multiple types like `u8x64` which really are better when hand-formatted.

There is a surprising amount of two-space indenting in this directory.

Non-trivial changes:
- `rustfmt::skip` needed in `debug-column.rs` to preserve meaning of the
  test.
- `rustfmt::skip` used in a few places where hand-formatting read more
  nicely: `enum/enum-match.rs`
- Line number adjustments needed for the expected output of
  `debug-column.rs` and `coroutine-debug.rs`.

tests/codegen/frame-pointer.rs

@@ -13,13 +13,12 @@
 
 #![feature(no_core, lang_items)]
 #![no_core]
-#[lang="sized"]
-trait Sized { }
-#[lang="copy"]
-trait Copy { }
+#[lang = "sized"]
+trait Sized {}
+#[lang = "copy"]
+trait Copy {}
 impl Copy for u32 {}
 
-
 // CHECK: define i32 @peach{{.*}}[[PEACH_ATTRS:\#[0-9]+]] {
 #[no_mangle]
 pub fn peach(x: u32) -> u32 {