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/VoldNativeService.h b/VoldNativeService.h
index 060d704..c7d8849 100644
--- a/VoldNativeService.h
+++ b/VoldNativeService.h
@@ -36,6 +36,7 @@
     binder::Status monitor();
     binder::Status reset();
     binder::Status shutdown();
+    binder::Status abortFuse();
 
     binder::Status onUserAdded(int32_t userId, int32_t userSerial);
     binder::Status onUserRemoved(int32_t userId);