chore: backport some empty block check fixes

Author: calebcartwright

src/expr.rs

@@ -429,7 +429,7 @@ fn rewrite_empty_block(
     prefix: &str,
     shape: Shape,
 ) -> Option<String> {
-    if !block.stmts.is_empty() {
+    if block_has_statements(&block) {
         return None;
     }
 

tests/source/issue_3868.rs

@@ -0,0 +1,13 @@
+fn foo() {
+    ;
+}
+
+fn bar() {
+    for _ in 0..1 {
+        ;
+    }
+}
+
+fn baz() {
+    ();
+    }

tests/target/issue_3868.rs

@@ -0,0 +1,9 @@
+fn foo() {}
+
+fn bar() {
+    for _ in 0..1 {}
+}
+
+fn baz() {
+    ();
+}