Fix build with Bison 3.7 and newer
https://github.com/verilator/verilator/commit/aa39d020d88dd1d5beb3810cf551ff879b7f88a4

Index: src/verilog.y
--- src/verilog.y.orig
+++ src/verilog.y
@@ -207,6 +207,15 @@ static void ERRSVKWD(FileLine* fileline, const string&
 class AstSenTree;
 %}
 
+// We run bison with the -d argument. This tells it to generate a
+// header file with token names. Old versions of bison pasted the
+// contents of that file into the generated source as well; newer
+// versions just include it.
+//
+// Since we run bison through ../bisonpre, it doesn't know the correct
+// header file name, so we need to tell it.
+BISONPRE_VERSION(3.7,%define api.header.include {"V3ParseBison.h"})
+
 // When writing Bison patterns we use yTOKEN instead of "token",
 // so Bison will error out on unknown "token"s.