cat: show \r\n as ^M$ when -E is enabled

This functionality was recently added to GNU cat, but had a bug.
This implementation will be commpatible with gnu once the bug in gnu is fixed.

tests/by-util/test_cat.rs

@@ -273,6 +273,14 @@ fn test_stdin_show_ends() {
             .stdout_only("\t\0$\n\t");
     }
 }
+#[test]
+fn test_show_ends_crlf() {
+    new_ucmd!()
+        .arg("-E")
+        .pipe_in("a\nb\r\n\rc\n\r\n\r")
+        .succeeds()
+        .stdout_only("a$\nb^M$\n\rc$\n^M$\n\r");
+}
 
 #[test]
 fn test_stdin_show_all() {