Move over to the C++ Fstab class

Test: build and boot
Change-Id: Id3850c9c133f6644073a2439368501253a2a94a9
diff --git a/VoldUtil.h b/VoldUtil.h
index 782e36d..173c598 100644
--- a/VoldUtil.h
+++ b/VoldUtil.h
@@ -14,14 +14,11 @@
  * limitations under the License.
  */
 
-#ifndef _VOLDUTIL_H
-#define _VOLDUTIL_H
+#pragma once
 
 #include <fstab/fstab.h>
 #include <sys/cdefs.h>
 
-extern struct fstab* fstab_default;
+extern android::fs_mgr::Fstab fstab_default;
 
 #define ARRAY_SIZE(a) (sizeof(a) / sizeof(*(a)))
-
-#endif