Include malloc.h from ocb.c

stdlib.h does not always provide memalign.

Bug: 110161494
Change-Id: I2939646fde7d22496a2162e5685fd4b793551bb9
diff --git a/key_blob_utils/ocb.c b/key_blob_utils/ocb.c
index 9a68182..70172c8 100644
--- a/key_blob_utils/ocb.c
+++ b/key_blob_utils/ocb.c
@@ -73,6 +73,7 @@
 /* ----------------------------------------------------------------------- */
 
 #include <keymaster/key_blob_utils/ae.h>
+#include <malloc.h>
 #include <stdlib.h>
 #include <string.h>