Report uncrypt errors in details

Add the error codes for uncrypt and report the failure details in
uncrypt_status.

Test: uncrypt_error logs correctly in last_install
Bug: 31603820
Change-Id: I8e0de845ce1707b6f8f5ae84564c5e93fd5f5ef5
(cherry picked from commit 0c68675f5ae80cd669e0bf014a69689b6fe08eee)
diff --git a/error_code.h b/error_code.h
index 92e93bd..dfea0eb 100644
--- a/error_code.h
+++ b/error_code.h
@@ -46,7 +46,7 @@
 
 enum UncryptErrorCode {
     kUncryptNoError = -1,
-    kUncryptErrorHolder = 50,
+    kUncryptErrorPlaceholder = 50,
     kUncryptTimeoutError = 100,
     kUncryptFileRemoveError,
     kUncryptFileOpenError,