add sndio driver

Index: platform/linuxbsd/os_linuxbsd.cpp
--- platform/linuxbsd/os_linuxbsd.cpp.orig
+++ platform/linuxbsd/os_linuxbsd.cpp
@@ -1183,6 +1183,10 @@ String OS_LinuxBSD::get_system_ca_certificates() {
 OS_LinuxBSD::OS_LinuxBSD() {
 	main_loop = nullptr;
 
+#ifdef SNDIO_ENABLED
+	AudioDriverManager::add_driver(&driver_sndio);
+#endif
+
 #ifdef PULSEAUDIO_ENABLED
 	AudioDriverManager::add_driver(&driver_pulseaudio);
 #endif
