fscrypt ENOKEY: ignore error and continue

Some files do not have a fscrypt key assigned to them when the fscrypt call is made to get the policy. Ignore the file when backing up in libtar.

Change-Id: I1054752ff332b27d0b3b1eeb288fdcc8112ab993
(cherry picked from commit b2a1f930edb37dc3c18a1df8085a3cc6c1d1ec01)
diff --git a/libtar/block.c b/libtar/block.c
index e94c24c..aaedc8e 100755
--- a/libtar/block.c
+++ b/libtar/block.c
@@ -719,7 +719,7 @@
 	}
 
 #ifdef DEBUG
-	LOG("th_write(): returning 0");
+	LOG("th_write(): returning 0\n");
 #endif
 	return 0;
 }