Define PRIVATE and add it to all global symbols so we don't export assembly functions.

libvpx/source/libvpx/vp8/encoder/x86/dct_mmx.asm

 ;
 ;  Copyright (c) 2010 The WebM project authors. All Rights Reserved.
 ;
 ;  Use of this source code is governed by a BSD-style license
 ;  that can be found in the LICENSE file in the root of the source
 ;  tree. An additional intellectual property rights grant can be found
 ;  in the file PATENTS.  All contributing project authors may
 ;  be found in the AUTHORS file in the root of the source tree.
 ;
 
 
 %include "vpx_ports/x86_abi_support.asm"
 
 ;void vp8_short_fdct4x4_mmx(short *input, short *output, int pitch)
-global sym(vp8_short_fdct4x4_mmx)
+global sym(vp8_short_fdct4x4_mmx) PRIVATE
 sym(vp8_short_fdct4x4_mmx):
     push        rbp
     mov         rbp,        rsp
     SHADOW_ARGS_TO_STACK 3
     GET_GOT     rbx
     push        rsi
     push        rdi
     ; end prolog
 
         mov         rsi,        arg(0)      ; input
@@ skipping 206 matching lines @@
     times 2 dd 14500
 align 8
 _7500:
     times 2 dd 7500
 align 8
 _12000:
     times 2 dd 12000
 align 8
 _51000:
     times 2 dd 51000