Bug 1385481 - Update cubeb from upstream to 42da8d2. r=kinetik

MozReview-Commit-ID: HOrC5Iwd92L

media/libcubeb/README_MOZILLA

@@ -5,4 +5,4 @@ Makefile.in build files for the Mozilla build system.
 
 The cubeb git repository is: git://github.com/kinetiknz/cubeb.git
 
-The git commit ID used was 09aeb59259487a2fbeeca1824f1f68f55b6787f4 (2017-07-22 09:54:44 +1200)
+The git commit ID used was cf622778bbc3d240d7079879fabd2dc945237cbc (2017-07-29 11:28:16 +1200)

media/libcubeb/src/cubeb_audiounit.cpp

@@ -590,6 +590,7 @@ audiounit_set_device_info(cubeb_stream * stm, AudioDeviceID id, io_side side)
     type = CUBEB_DEVICE_TYPE_OUTPUT;
   }
   memset(info, 0, sizeof(device_info));
+  info->id = id;
 
   if (side == INPUT) {
     info->flags |= DEV_INPUT;