netbsdaudio: Handle ioctls failing

A user reported that the mpv video player hangs after attempting to
set an unsupported number of channels with the SDL audio output,
because it thinks it's successfully opened the device. This makes
the failure graceful.

src/audio/netbsd/SDL_netbsdaudio.c

@@ -295,9 +295,13 @@ NETBSDAUDIO_OpenDevice(_THIS, void *handle, const char *devname, int iscapture)
 
     info.hiwat = 5;
     info.lowat = 3;
-    (void) ioctl(this->hidden->audio_fd, AUDIO_SETINFO, &info);
+    if (ioctl(this->hidden->audio_fd, AUDIO_SETINFO, &info) < 0) {
+        return SDL_SetError("AUDIO_SETINFO failed for %s: %s", devname, strerror(errno));
+    }
 
-    (void) ioctl(this->hidden->audio_fd, AUDIO_GETINFO, &info);
+    if (ioctl(this->hidden->audio_fd, AUDIO_GETINFO, &info) < 0) {
+        return SDL_SetError("AUDIO_GETINFO failed for %s: %s", devname, strerror(errno));
+    }
 
     /* Final spec used for the device. */
     this->spec.format = format;