Quieten -Wempty-body with equivalent while loop

Although correct, the empty for loop is a bit misleading.

Don't disable -Wempty-body because it's actually useful. Sprinkling
the code with pragmas to disable a certain warning for a certain
compiler is not a good idea either.

Author: mhaas

src/conf.c

@@ -863,7 +863,10 @@ void parse_trusted_mac_list(const char *ptr) {
 					config.trustedmaclist->next = NULL;
 				} else {
 				/* Advance to the last entry */
-				for (p = config.trustedmaclist; p->next != NULL; p = p->next);
+				p = config.trustedmaclist;
+				while (p->next != NULL) {
+					p = p->next;
+				}
 				p->next = safe_malloc(sizeof(t_trusted_mac));
 				p = p->next;
 				p->mac = safe_strdup(mac);