Fix iOS GN build and cleanup system_wrappers

webrtc/system_wrappers/source/atomic32_mac.cc

Index: webrtc/system_wrappers/source/atomic32_mac.cc
diff --git a/webrtc/system_wrappers/source/atomic32_mac.cc b/webrtc/system_wrappers/source/atomic32_mac.cc
deleted file mode 100644
index 7c77d092b55f694663f0f8e54038ccb13770c95c..0000000000000000000000000000000000000000
--- a/webrtc/system_wrappers/source/atomic32_mac.cc
+++ /dev/null
@@ -1,49 +0,0 @@
-/*
- *  Copyright (c) 2012 The WebRTC 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 "webrtc/system_wrappers/include/atomic32.h"
-
-#include <assert.h>
-#include <libkern/OSAtomic.h>
-#include <stdlib.h>
-
-#include "webrtc/common_types.h"
-
-namespace webrtc {
-
-Atomic32::Atomic32(int32_t initial_value)
-    : value_(initial_value) {
-  assert(Is32bitAligned());
-}
-
-Atomic32::~Atomic32() {
-}
-
-int32_t Atomic32::operator++() {
-  return OSAtomicIncrement32Barrier(&value_);
-}
-
-int32_t Atomic32::operator--() {
-  return OSAtomicDecrement32Barrier(&value_);
-}
-
-int32_t Atomic32::operator+=(int32_t value) {
-  return OSAtomicAdd32Barrier(value, &value_);
-}
-
-int32_t Atomic32::operator-=(int32_t value) {
-  return OSAtomicAdd32Barrier(-value, &value_);
-}
-
-bool Atomic32::CompareExchange(int32_t new_value, int32_t compare_value) {
-  return OSAtomicCompareAndSwap32Barrier(compare_value, new_value, &value_);
-}
-
-}  // namespace webrtc