[iter] Add operator << to set / vector

src/hb-set.hh

@@ -373,6 +373,9 @@ struct hb_set_t
   /* Predicate. */
   bool operator () (hb_codepoint_t k) const { return has (k); }
 
+  /* Sink interface. */
+  hb_set_t& operator << (hb_codepoint_t v) { add (v); return *this; }
+
   bool intersects (hb_codepoint_t first, hb_codepoint_t last) const
   {
     hb_codepoint_t c = first - 1;

src/hb-vector.hh

@@ -89,6 +89,9 @@ struct hb_vector_t
 
   explicit_operator bool () const { return length; }
 
+  /* Sink interface. */
+  hb_vector_t& operator << (const Type &v) { push (v); return *this; }
+
   hb_array_t<      Type> as_array ()       { return hb_array (arrayZ(), length); }
   hb_array_t<const Type> as_array () const { return hb_array (arrayZ(), length); }