+# If any were specifically requested disabled, do it.
+AS_IF([test "x$with_jack" = "xno"], [systems=`echo $systems|tr ' ' \\\\n|grep -v jack`])
+AS_IF([test "x$with_alsa" = "xno"], [systems=`echo $systems|tr ' ' \\\\n|grep -v alsa`])
+AS_IF([test "x$with_pulse" = "xno"], [systems=`echo $systems|tr ' ' \\\\n|grep -v pulse`])
+AS_IF([test "x$with_oss" = "xno"], [systems=`echo $systems|tr ' ' \\\\n|grep -v oss`])
+AS_IF([test "x$with_core" = "xno"], [systems=`echo $systems|tr ' ' \\\\n|grep -v core`])
+AS_IF([test "x$with_asio" = "xno"], [systems=`echo $systems|tr ' ' \\\\n|grep -v asio`])
+AS_IF([test "x$with_dsound" = "xno"], [systems=`echo $systems|tr ' ' \\\\n|grep -v dsound`])
+AS_IF([test "x$with_wasapi" = "xno"], [systems=`echo $systems|tr ' ' \\\\n|grep -v wasapi`])
+systems=" `echo $systems|tr \\\\n ' '` "
+