Use size_t for return value from fwrite.

TBR=sgjesse@chromium.org
Review URL: http://codereview.chromium.org/4033005

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@5695 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/log.cc

@@ -1378,7 +1378,7 @@ void Logger::LogCodeInfo() {
 void Logger::LowLevelCodeCreateEvent(Code* code, LogMessageBuilder* msg) {
   if (!FLAG_ll_prof || Log::output_code_handle_ == NULL) return;
   int pos = static_cast<int>(ftell(Log::output_code_handle_));
-  int rv = fwrite(code->instruction_start(), 1, code->instruction_size(),
+  size_t rv = fwrite(code->instruction_start(), 1, code->instruction_size(),
                      Log::output_code_handle_);
   ASSERT(static_cast<size_t>(code->instruction_size()) == rv);
   USE(rv);