vold: Support aborting FUSE connections.

This can be done through binder as well as vdc, using 'vdc volume
abort_fuse'.

Bug: 153411204
Test: adb shell vdc volume abort_fuse
Change-Id: I93e46dc1cd361729cc1162c63520cf73152ea409
diff --git a/binder/android/os/IVold.aidl b/binder/android/os/IVold.aidl
index 68e2ba9..6d14959 100644
--- a/binder/android/os/IVold.aidl
+++ b/binder/android/os/IVold.aidl
@@ -25,6 +25,7 @@
 interface IVold {
     void setListener(IVoldListener listener);
 
+    void abortFuse();
     void monitor();
     void reset();
     void shutdown();