Use FormatMessageW for Windows error messages to handle internationalized messages correctly.

runtime/bin/platform_macos.cc

Index: runtime/bin/platform_macos.cc
diff --git a/runtime/bin/platform_macos.cc b/runtime/bin/platform_macos.cc
index 822399d7328ce1fafd80eb61b423c10854c8f31c..87e8c6fb44609965dc99f0a0ad687c084dffc1ae 100644
--- a/runtime/bin/platform_macos.cc
+++ b/runtime/bin/platform_macos.cc
@@ -70,12 +70,3 @@ char** Platform::Environment(intptr_t* count) {
 void Platform::FreeEnvironment(char** env, intptr_t count) {
   delete[] env;
 }
-
-
-char* Platform::StrError(int error_code) {
-  static const int kBufferSize = 1024;
-  char* error = static_cast<char*>(malloc(kBufferSize));
-  error[0] = '\0';
-  strerror_r(error_code, error, kBufferSize);
-  return error;
-}