OS-1840 fmdump shall emit JSON (rm feedback)

@@ -45,11 +45,11 @@
 extern int nvpair_value_match(nvpair_t *, int, char *, char **);
 extern int nvpair_value_match_regex(nvpair_t *, int, char *, regex_t *,
     char **);
 
 extern void nvlist_print(FILE *, nvlist_t *);
-extern void nvlist_print_json(FILE *, nvlist_t *);
+extern int nvlist_print_json(FILE *, nvlist_t *);
 extern void dump_nvlist(nvlist_t *, int);
 
 /*
  * Private nvlist printing interface that allows the caller some control
  * over output rendering (as opposed to nvlist_print and dump_nvlist).