Add test for issue 4635

Closes 4635

It's unclear which commit resolved this, but the original issue cannot
be reproduced.

Author: ytmimi

tests/target/issue_4635.rs

@@ -0,0 +1,5 @@
+fn main() {
+    println!("");
+    println!("" /* " */);
+    println!("" /* \" */);
+}