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/array-cmp.rs

@@ -10,9 +10,10 @@
 #[no_mangle]
 pub fn compare() -> bool {
     let bytes = 12.5f32.to_ne_bytes();
-    bytes == if cfg!(target_endian = "big") {
-        [0x41, 0x48, 0x00, 0x00]
-    } else {
-        [0x00, 0x00, 0x48, 0x41]
-    }
+    bytes
+        == if cfg!(target_endian = "big") {
+            [0x41, 0x48, 0x00, 0x00]
+        } else {
+            [0x00, 0x00, 0x48, 0x41]
+        }
 }