Do not build an extra identical structure (#2440)

This makes the code more complex than needed.

Part of a clippy lint being developed.

Author: samueltardieu

Diff for: bindgen/regex_set.rs

@@ -19,9 +19,7 @@ pub struct RegexSet {
 impl RegexSet {
     /// Create a new RegexSet
     pub fn new() -> RegexSet {
-        RegexSet {
-            ..Default::default()
-        }
+        RegexSet::default()
     }
 
     /// Is this set empty?