move JACK audio backend to its own folder and adjust build system to reflect that (installed version may now work)

libs/backends/wscript

@@ -0,0 +1,27 @@
+#!/usr/bin/env python
+from waflib.extras import autowaf as autowaf
+import os
+
+# Mandatory variables
+top = '.'
+out = 'build'
+
+backends = [ 'jack' ]
+
+def options(opt):
+    autowaf.set_options(opt)
+
+def sub_config_and_use(conf, name, has_objects = True):
+    conf.recurse(name)
+    autowaf.set_local_lib(conf, name, has_objects)
+
+def configure(conf):
+    autowaf.set_recursive()
+    autowaf.configure(conf)
+
+    for i in backends:
+        sub_config_and_use(conf, i)
+
+def build(bld):
+    for i in backends:
+        bld.recurse(i)