Fix if-else syntax for the case missing OSS support

(cherry picked from commit dd6da7345a)

libtdemid/deviceman.cc

@@ -705,9 +705,7 @@ void DeviceManager::seqbuf_dump (void)
 void DeviceManager::seqbuf_clean(void)
 {
 #ifdef HAVE_ALSA_SUPPORT
-  if (alsa)
+  if (alsa) { ((AlsaOut *)device[default_dev])->seqbuf_clean(); return ; }
-    ((AlsaOut *)device[default_dev])->seqbuf_clean();
-  else
 #endif
 #ifdef HAVE_OSS_SUPPORT
     _seqbufptr=0;