ext/json/parser/prereq.mk: Add a "automatically generated" header

to parser.c.

ext/json/parser/parser.c

@@ -1,3 +1,4 @@
+/* This file is automatically generated from parser.rl by using ragel */
 
 #line 1 "parser.rl"
 #include "../fbuffer/fbuffer.h"

ext/json/parser/prereq.mk

@@ -5,6 +5,7 @@ RAGEL = ragel
 .rl.c:
 	$(RAGEL) -G2 $<
 	$(BASERUBY) -pli -e '$$_.sub!(/[ \t]+$$/, "")' \
-	-e '$$_.sub!(/^static const int (JSON_.*=.*);$$/, "enum {\\1};")' $@
+	-e '$$_.sub!(/^static const int (JSON_.*=.*);$$/, "enum {\\1};")' \
+	-e '$$header ||= $$_ = "/* This file is automatically generated from parser.rl by using ragel */\n" + $$_' $@
 
 parser.c: