Roll nasm 20920a85609b..a0a6951e259b (3 commits)

https://chromium.googlesource.com/chromium/deps/nasm.git/+log/20920a85609b..a0a6951e259b

This is a manual roll to integrate MSVC warnings suppressions.
It makes Chromium->WebRTC autoroller happy.
It doesn't matter for Chromium itself which uses clang even on Windows.

Bug: webrtc:9530
Change-Id: I7b0358e16b243b2bb400a1cf3d89c5a14cec14de
Reviewed-on: https://chromium-review.googlesource.com/c/1329966Reviewed-by: David Benjamin <davidben@chromium.org>
Commit-Queue: Yves Gerey <yvesg@google.com>
Cr-Commit-Position: refs/heads/master@{#607291}

DEPS

@@ -963,7 +963,7 @@ deps = {
 
   'src/third_party/nasm': {
       'url': Var('chromium_git') + '/chromium/deps/nasm.git' + '@' +
-      '20920a85609b0608d4c9c80b525196d07183b289'
+      'a0a6951e259bd347c133969740348bb5ebb468c4'
   },
 
   'src/third_party/netty-tcnative/src': {