Grab bag of clang fixes for Windows code

third_party/leveldatabase/port/port_chromium.h

 // Copyright (c) 2011 The LevelDB Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file. See the AUTHORS file for names of contributors.
 //
 // See port_example.h for documentation for the following types/functions.
 
 #ifndef STORAGE_LEVELDB_PORT_PORT_CHROMIUM_H_
 #define STORAGE_LEVELDB_PORT_PORT_CHROMIUM_H_
 
 #include <stdint.h>
 #include <string>
 #include <cstring>
 #include "base/atomicops.h"
 #include "base/basictypes.h"
 #include "base/synchronization/condition_variable.h"
 #include "base/synchronization/lock.h"
 
 // Linux's ThreadIdentifier() needs this.
 #if defined(OS_LINUX)
 #  include <linux/unistd.h>
 #endif
 
 #if defined(OS_WIN)
 #define snprintf _snprintf
-#define va_copy(a, b) do { (a) = (b); } while (0)
+#if !defined(__clang__)
+# define va_copy(a, b) do { (a) = (b); } while (0)
+#endif
 #endif
 
 namespace leveldb {
 namespace port {
 
 // Chromium only supports little endian.
 static const bool kLittleEndian = true;
 
 class Mutex {
  public:
@@ skipping 73 matching lines @@
                        char* output);
 
 inline bool GetHeapProfile(void (*func)(void*, const char*, int), void* arg) {
   return false;
 }
 
 }
 }
 
 #endif  // STORAGE_LEVELDB_PORT_PORT_CHROMIUM_H_