mdb.c changes for monero

diff --git a/external/db_drivers/liblmdb/mdb.c b/external/db_drivers/liblmdb/mdb.c
index b3de970..662f38f 100644
--- a/external/db_drivers/liblmdb/mdb.c
+++ b/external/db_drivers/liblmdb/mdb.c
@@ -312,6 +312,12 @@ union semun {
 # endif
 #endif /* MDB_USE_ROBUST */

+#ifdef PTHREAD_MUTEX_ROBUST_NP
+#define PTHREAD_MUTEX_ROBUST PTHREAD_MUTEX_ROBUST_NP
+#define pthread_mutexattr_setrobust pthread_mutexattr_setrobust_np
+#define pthread_mutex_consistent pthread_mutex_consistent_np
+#endif
+
 #if defined(MDB_OWNERDEAD) && MDB_USE_ROBUST
 #define MDB_ROBUST_SUPPORTED   1
 #endif