Add static / void qualifiers.

Author: ioquatix

ext/io/event/selector/epoll.c

@@ -1035,7 +1035,7 @@ VALUE IO_Event_Selector_EPoll_wakeup(VALUE self) {
 	return Qfalse;
 }
 
-int IO_Event_Selector_EPoll_supported_p() {
+static int IO_Event_Selector_EPoll_supported_p(void) {
 	int fd = epoll_create1(EPOLL_CLOEXEC);
 
 	if (fd < 0) {

ext/io/event/selector/kqueue.c

@@ -1046,7 +1046,7 @@ VALUE IO_Event_Selector_KQueue_wakeup(VALUE self) {
 }
 
 
-int IO_Event_Selector_KQueue_supported_p() {
+static int IO_Event_Selector_KQueue_supported_p(void) {
 	int fd = kqueue();
 
 	if (fd < 0) {

ext/io/event/selector/uring.c

@@ -1175,7 +1175,7 @@ VALUE IO_Event_Selector_URing_wakeup(VALUE self) {
 
 #pragma mark - Native Methods
 
-int IO_Event_Selector_URing_supported_p() {
+static int IO_Event_Selector_URing_supported_p(void) {
 	struct io_uring ring;
 	int result = io_uring_queue_init(1, &ring, 0);