Go through all event devices, not just event[0-32]

There are no guarantees that joypads are in event0-event32
range.  Some devices, such as laptops with detachable keyboards
and wacom can reserve events all the way up to 32.

Some udev rules with e.g. custom controller firmwares may
load the device as /dev/input/eventX, where X is greater than
32.

This patch uses POSIX dirent to enumerate the event devices, so
entries outside 0-32 range are not skipped.

(cherry picked from commit 01c030f9b79ab8bb402b286704d4d58908d6d03c)

platform/x11/joypad_linux.cpp

@@ -32,6 +32,7 @@
 
 #include "joypad_linux.h"
 
+#include <dirent.h>
 #include <errno.h>
 #include <fcntl.h>
 #include <linux/input.h>
@@ -205,13 +206,24 @@ void JoypadLinux::monitor_joypads() {
 
 	while (!exit_udev) {
 		joy_mutex->lock();
-		for (int i = 0; i < 32; i++) {
+
+		DIR *input_directory;
+		input_directory = opendir("/dev/input");
+		if (input_directory) {
+			struct dirent *current;
 			char fname[64];
-			sprintf(fname, "/dev/input/event%d", i);
-			if (attached_devices.find(fname) == -1) {
-				open_joypad(fname);
+
+			while ((current = readdir(input_directory)) != NULL) {
+				if (strncmp(current->d_name, "event", 5) != 0) {
+					continue;
+				}
+				sprintf(fname, "/dev/input/%.*s", 16, current->d_name);
+				if (attached_devices.find(fname) == -1) {
+					open_joypad(fname);
+				}
 			}
 		}
+		closedir(input_directory);
 		joy_mutex->unlock();
 		usleep(1000000); // 1s
 	}