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/binary-search-index-no-bound-check.rs

@@ -11,11 +11,7 @@ pub fn binary_search_index_no_bounds_check(s: &[u8]) -> u8 {
     // CHECK-NOT: slice_start_index_len_fail
     // CHECK-NOT: slice_end_index_len_fail
     // CHECK-NOT: panic_bounds_check
-    if let Ok(idx) = s.binary_search(&b'\\') {
-        s[idx]
-    } else {
-        42
-    }
+    if let Ok(idx) = s.binary_search(&b'\\') { s[idx] } else { 42 }
 }
 
 // Similarly, check that `partition_point` is known to return a valid fencepost.