Rename all files/classes shared by Linux and Mac to Posix.

Besides being a good idea in general, this lets us use the good chromium_code==1 warning settings on Mac and Windows. Straight rename except for a change to use os_posix in the gyp files.
Review URL: http://webrtc-codereview.appspot.com/88011

git-svn-id: http://webrtc.googlecode.com/svn/trunk@282 4adac7df-926f-26a2-2b94-8c16560cd09d

src/system_wrappers/source/rw_lock_posix.h

@@ -0,0 +1,39 @@
+/*
+ *  Copyright (c) 2011 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.
+ */
+
+#ifndef WEBRTC_SYSTEM_WRAPPERS_SOURCE_RW_LOCK_POSIX_H_
+#define WEBRTC_SYSTEM_WRAPPERS_SOURCE_RW_LOCK_POSIX_H_
+
+#include "rw_lock_wrapper.h"
+
+#include <pthread.h>
+
+namespace webrtc {
+class RWLockPosix : public RWLockWrapper
+{
+public:
+    RWLockPosix();
+    virtual ~RWLockPosix();
+
+    virtual void AcquireLockExclusive();
+    virtual void ReleaseLockExclusive();
+
+    virtual void AcquireLockShared();
+    virtual void ReleaseLockShared();
+
+protected:
+    virtual int Init();
+
+private:
+    pthread_rwlock_t _lock;
+};
+} // namespace webrtc
+
+#endif // WEBRTC_SYSTEM_WRAPPERS_SOURCE_RW_LOCK_POSIX_H_