Add supportsCheckpoint

This returns true if any entries in the fstab have checkpoint=
set.

Test: Call vdc checkpoint supportsCheckpoint. Should return 1
      iff an fstab entry has checkpoint=fs or checkpoint=block set
Bug: 111020314

Change-Id: Ic79bc96ded4da6605f73992dcff542e7cb50d705
diff --git a/VoldNativeService.cpp b/VoldNativeService.cpp
index c58ff01..1001d2b 100644
--- a/VoldNativeService.cpp
+++ b/VoldNativeService.cpp
@@ -864,5 +864,12 @@
     return cp_abortChanges();
 }
 
+binder::Status VoldNativeService::supportsCheckpoint(bool* _aidl_return) {
+    ENFORCE_UID(AID_SYSTEM);
+    ACQUIRE_LOCK;
+
+    return cp_supportsCheckpoint(*_aidl_return);
+}
+
 }  // namespace vold
 }  // namespace android