Add NULL argument to SNDCTL_DSP_NONBLOCK ioctl call

Comes from here:
http://cvsweb.netbsd.org/bsdweb.cgi/pkgsrc/emulators/qemu/patches/patch-am?rev=1.2&content-type=text/x-cvsweb-markup

http://manuals.opensound.com/developer/SNDCTL_DSP_NONBLOCK.html
No explanation for NULL given.

git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@4825 c046a42c-6fe2-441c-8c8c-71466251a162

audio/ossaudio.c

@@ -237,7 +237,7 @@ static int oss_open (int in, struct oss_params *req,
         goto err;
     }
 
-    if (ioctl (fd, SNDCTL_DSP_NONBLOCK)) {
+    if (ioctl (fd, SNDCTL_DSP_NONBLOCK, NULL)) {
         oss_logerr2 (errno, typ, "Failed to set non-blocking mode\n");
         goto err;
     }