d: fix use of b4_union_members

[Akim Demaille]

commit 10e3ccac05eafe837e68892c21e18babc6c824e6
Author: Akim Demaille <address@hidden>
Date:   Thu Dec 6 05:42:12 2018 +0100

    d: fix use of b4_union_members
    
    * data/lalr1.d: Use b4_user_union_members instead.

diff --git a/data/lalr1.d b/data/lalr1.d
index b70eb135..04b48e0e 100644
--- a/data/lalr1.d
+++ b/data/lalr1.d
@@ -223,9 +223,9 @@ public class ]b4_location_type[
 
 private immutable bool yy_location_is_class = true;
 
-]]))m4_ifdef([b4_union_members], [private union YYSemanticType
+]]))m4_ifdef([b4_user_union_members], [private union YYSemanticType
 {
-b4_union_members
+b4_user_union_members
 };
 
 ]m4_if(b4_tag_seen_flag, 0,