diff -rup gcc-6.4.0/gcc/ada/s-osinte-linux.ads gcc-6.4.0-new/gcc/ada/s-osinte-linux.ads
--- gcc-6.4.0/gcc/ada/s-osinte-linux.ads	2015-10-16 06:25:00.234638000 -0700
+++ gcc-6.4.0-new/gcc/ada/s-osinte-linux.ads	2018-09-06 13:47:24.620560129 -0700
@@ -393,12 +393,6 @@ package System.OS_Interface is
    PTHREAD_RWLOCK_PREFER_WRITER_NP              : constant := 1;
    PTHREAD_RWLOCK_PREFER_WRITER_NONRECURSIVE_NP : constant := 2;
 
-   function pthread_rwlockattr_setkind_np
-     (attr : access pthread_rwlockattr_t;
-      pref : int) return int;
-   pragma Import
-     (C, pthread_rwlockattr_setkind_np, "pthread_rwlockattr_setkind_np");
-
    function pthread_rwlock_init
      (mutex : access pthread_rwlock_t;
       attr  : access pthread_rwlockattr_t) return int;
diff -rup gcc-6.4.0/gcc/ada/s-taprop-linux.adb gcc-6.4.0-new/gcc/ada/s-taprop-linux.adb
--- gcc-6.4.0/gcc/ada/s-taprop-linux.adb	2015-10-16 06:25:00.234638000 -0700
+++ gcc-6.4.0-new/gcc/ada/s-taprop-linux.adb	2018-09-06 13:49:49.113896910 -0700
@@ -277,11 +277,6 @@ package body System.Task_Primitives.Oper
             Result := pthread_rwlockattr_init (RWlock_Attr'Access);
             pragma Assert (Result = 0);
 
-            Result := pthread_rwlockattr_setkind_np
-              (RWlock_Attr'Access,
-               PTHREAD_RWLOCK_PREFER_WRITER_NONRECURSIVE_NP);
-            pragma Assert (Result = 0);
-
             Result := pthread_rwlock_init (L.RW'Access, RWlock_Attr'Access);
 
             pragma Assert (Result = 0 or else Result = ENOMEM);