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/vdc.cpp b/vdc.cpp
index e971d52..35775a7 100644
--- a/vdc.cpp
+++ b/vdc.cpp
@@ -105,6 +105,10 @@
         checkStatus(vold->mountFstab(args[2]));
     } else if (args[0] == "cryptfs" && args[1] == "encryptFstab" && args.size() == 3) {
         checkStatus(vold->encryptFstab(args[2]));
+    } else if (args[0] == "checkpoint" && args[1] == "supportsCheckpoint" && args.size() == 2) {
+        bool supported = false;
+        checkStatus(vold->supportsCheckpoint(&supported));
+        return supported ? 1 : 0;
     } else if (args[0] == "checkpoint" && args[1] == "startCheckpoint" && args.size() == 3) {
         int retry;
         if (!android::base::ParseInt(args[2], &retry)) exit(EINVAL);