Fix the only occurrence of using void function as argument to return()

When a function returns void, it can be used as an argument to return in
function returning also void, e.g.:

void in(void) {
  return;
}

void out(void) {
  return (in());
}

while this is legal, it should be rewritten as:

void out(void) {
  in();
  return;
}

The semantic patch just find the occurrences, and they need to be fixed
by hand.

cocci/return-void-from-void.spatch

@@ -0,0 +1,19 @@
+@ rule1 @
+identifier f1;
+@@
+
+void f1(...)
+{
+...
+}
+
+@ rule2 @
+identifier rule1.f1;
+identifier f2;
+@@
+
+void f2(...) {
+...
+* return(f1(...));
+...
+}

lib/isccfg/parser.c

@@ -1022,7 +1022,8 @@ cfg_print_duration(cfg_printer_t *pctx, const cfg_obj_t *obj) {
 
 	/* If this is not an ISO 8601 duration, just print it as a number. */
 	if (!duration.iso8601) {
-		return (cfg_print_rawuint(pctx, duration.parts[6]));
+		cfg_print_rawuint(pctx, duration.parts[6]);
+		return;
 	}
 
 	/* Calculate length of string. */