checkpatch.pl: forbid illegal empty lines after break;

This patch lets checkpatch.pl forbid illegal empty lines after break;.

Forbidden empty lines are categorized into 2 types:
1. empty lines after break; in a switch statement
2. empty lines after last break; in a compound statement

For example, a patch which contains diffs like this:
+void test(void)
+{
+	switch (x) {
+	case X:
+		break;		/* treated as an error */
+
+	case Y:
+		break;
+	default:
+		break;		/* treated as an error */
+
+	}
+
+	for ( ; ; ) {
+		if (0) {
+			break;	/* treated as an error */
+
+		}
+	}
+}
causes an error.

Signed-off-by: Hitoshi Mitake <mitake.hitoshi@lab.ntt.co.jp>