Be more C++. volume UUID should always be std::string.

Test: boots
Bug: 67041047
Change-Id: I36d3944ae8de192703b9ee359900841b833fe3a1
diff --git a/cryptfs.cpp b/cryptfs.cpp
index 2574e39..08a3d16 100644
--- a/cryptfs.cpp
+++ b/cryptfs.cpp
@@ -38,6 +38,7 @@
 #include <openssl/evp.h>
 #include <openssl/sha.h>
 #include <errno.h>
+#include <ext4_utils/ext4_crypt.h>
 #include <ext4_utils/ext4_utils.h>
 #include <linux/kdev_t.h>
 #include <fs_mgr.h>