src: fix compiler warning in node_os

Currently the following compiler warnings is generated:
../src/node_os.cc:167:24:
warning: comparison of integers of different signs: 'size_t'
(aka 'unsigned long') and 'int' [-Wsign-compare]
  for (size_t i = 0; i < count; i++) {
                     ~ ^ ~~~~~
1 warning generated.

This commit changes the type of i to int.

PR-URL: #24356
Reviewed-By: Michaël Zasso <targos@protonmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>
Reviewed-By: Gus Caplan <me@gus.host>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>

src/node_os.cc

@@ -163,7 +163,7 @@ static void GetCPUInfo(const FunctionCallbackInfo<Value>& args) {
   // The array is in the format
   // [model, speed, (5 entries of cpu_times), model2, speed2, ...]
   std::vector<Local<Value>> result(count * 7);
-  for (size_t i = 0; i < count; i++) {
+  for (int i = 0; i < count; i++) {
     uv_cpu_info_t* ci = cpu_infos + i;
     result[i * 7] = OneByteString(isolate, ci->model);
     result[i * 7 + 1] = Number::New(isolate, ci->speed);