Compile pgenmain.c and printgrammar.c with PGEN defined
diff --git a/Parser/printgrammar.c b/Parser/printgrammar.c
index 01f552f..dd7e6ae 100644
--- a/Parser/printgrammar.c
+++ b/Parser/printgrammar.c
@@ -1,6 +1,8 @@
 
 /* Print a bunch of C initializers that represent a grammar */
 
+#define PGEN
+
 #include "pgenheaders.h"
 #include "grammar.h"