Comments in structs use appropriate style

Fixes #491

src/expr.rs

@@ -1335,7 +1335,10 @@ fn rewrite_struct_lit<'a>(context: &RewriteContext,
         },
         indent: indent,
         width: budget,
-        ends_with_newline: false,
+        ends_with_newline: match context.config.struct_lit_style {
+            StructLitStyle::Block => true,
+            StructLitStyle::Visual => false,
+        },
         config: context.config,
     };
     let fields_str = try_opt!(write_list(&item_vec, &fmt));

tests/source/struct_lits_multiline.rs

@@ -71,3 +71,10 @@ fn issue201() {
 fn issue201_2() {
     let s = S{a: S2{    .. c}, ..  b};
 }
+
+fn issue491() {
+    Foo {
+        guard: None,
+        arm: 0, // Comment
+    };
+}

tests/target/struct_lits.rs

@@ -25,7 +25,7 @@ fn main() {
         // Comment
         a: foo(), // Comment
         // Comment
-        b: bar(), /* Comment */
+        b: bar(), // Comment
     };
 
     Foo { a: Bar, b: f() };

tests/target/struct_lits_multiline.rs

@@ -32,7 +32,7 @@ fn main() {
         // Comment
         a: foo(), // Comment
         // Comment
-        b: bar(), /* Comment */
+        b: bar(), // Comment
     };
 
     Foo {
@@ -107,3 +107,10 @@ fn issue201_2() {
         ..b
     };
 }
+
+fn issue491() {
+    Foo {
+        guard: None,
+        arm: 0, // Comment
+    };
+}