Fixing clang warnings.

posix/safe_strerror.cc

 // Copyright (c) 2006-2009 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #if defined(__ANDROID__)
 // Post-L versions of bionic define the GNU-specific strerror_r if _GNU_SOURCE
 // is defined, but the symbol is renamed to __gnu_strerror_r which only exists
 // on those later versions. To preserve ABI compatibility with older versions,
 // undefine _GNU_SOURCE and use the POSIX version.
 #undef _GNU_SOURCE
 #endif
 
 #include "base/posix/safe_strerror.h"
 
 #include <errno.h>
 #include <stdio.h>
 #include <string.h>
 
 #include "build/build_config.h"
 
 namespace base {
 
-#define USE_HISTORICAL_STRERRO_R (defined(__GLIBC__) || defined(OS_NACL))
+#if defined(__GLIBC__) || defined(OS_NACL)
+#define USE_HISTORICAL_STRERRO_R 1
+#else
+#define USE_HISTORICAL_STRERRO_R 0
+#endif
 
 #if USE_HISTORICAL_STRERRO_R && defined(__GNUC__)
 // GCC will complain about the unused second wrap function unless we tell it
 // that we meant for them to be potentially unused, which is exactly what this
 // attribute is for.
 #define POSSIBLY_UNUSED __attribute__((unused))
 #else
 #define POSSIBLY_UNUSED
 #endif
 
@@ skipping 81 matching lines @@
 }
 
 std::string safe_strerror(int err) {
   const int buffer_size = 256;
   char buf[buffer_size];
   safe_strerror_r(err, buf, sizeof(buf));
   return std::string(buf);
 }
 
 }  // namespace base