Add generic json

Author: Nikita Glukhov

src/backend/utils/adt/Makefile

@@ -44,6 +44,7 @@ OBJS = \
 	int.o \
 	int8.o \
 	json.o \
+	json_generic.o \
 	jsonb.o \
 	jsonb_gin.o \
 	jsonb_op.o \

src/backend/utils/adt/json.c

@@ -24,6 +24,7 @@
 #include "utils/datetime.h"
 #include "utils/json.h"
 #include "utils/jsonfuncs.h"
+#include "utils/json_generic.h"
 #include "utils/lsyscache.h"
 #include "utils/typcache.h"