Revert "[map] Make hb_map_set() return bool"

This reverts commit 7bf1980146cfc081b06264ac367b23ae9397adf1.
diff --git a/src/hb-map.cc b/src/hb-map.cc
index 9c7ad78..4f50828 100644
--- a/src/hb-map.cc
+++ b/src/hb-map.cc
@@ -170,12 +170,12 @@
  *
  * Since: REPLACEME
  **/
-hb_bool_t
+void
 hb_map_set (hb_map_t       *map,
 	    hb_codepoint_t  key,
 	    hb_codepoint_t  value)
 {
-  return map->set (key, value);
+  map->set (key, value);
 }
 
 /**