audio/sdl: return on error

Signed-off-by: malc <av1474@comtv.ru>
diff --git a/audio/sdlaudio.c b/audio/sdlaudio.c
index 0f23fd3..b74dcfa 100644
--- a/audio/sdlaudio.c
+++ b/audio/sdlaudio.c
@@ -191,6 +191,7 @@
     err = sigfillset (&new);
     if (err) {
         dolog ("sdl_open: sigfillset failed: %s\n", strerror (errno));
+        return -1;
     }
     err = pthread_sigmask (SIG_BLOCK, &new, &old);
     if (err) {