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/sparc-struct-abi.rs

@@ -6,12 +6,12 @@
 #![feature(no_core, lang_items)]
 #![no_core]
 
-#[lang="sized"]
-trait Sized { }
-#[lang="freeze"]
-trait Freeze { }
-#[lang="copy"]
-trait Copy { }
+#[lang = "sized"]
+trait Sized {}
+#[lang = "freeze"]
+trait Freeze {}
+#[lang = "copy"]
+trait Copy {}
 
 #[repr(C)]
 pub struct Bool {
@@ -26,7 +26,6 @@ pub extern "C" fn structbool() -> Bool {
     Bool { b: true }
 }
 
-
 #[repr(C)]
 pub struct BoolFloat {
     b: bool,
@@ -44,8 +43,7 @@ pub extern "C" fn structboolfloat() -> BoolFloat {
 // CHECK: define void @structboolfloat_input({ i32, float } inreg %0)
 // CHECK-NEXT: start:
 #[no_mangle]
-pub extern "C" fn structboolfloat_input(a: BoolFloat) { }
-
+pub extern "C" fn structboolfloat_input(a: BoolFloat) {}
 
 #[repr(C)]
 pub struct ShortDouble {
@@ -64,8 +62,7 @@ pub extern "C" fn structshortdouble() -> ShortDouble {
 // CHECK: define void @structshortdouble_input({ i64, double } %0)
 // CHECK-NEXT: start:
 #[no_mangle]
-pub extern "C" fn structshortdouble_input(a: ShortDouble) { }
-
+pub extern "C" fn structshortdouble_input(a: ShortDouble) {}
 
 #[repr(C)]
 pub struct FloatLongFloat {