src: initialize pid variable before goto

This fixes an error when compiling with clang-cl on Windows:

```
src/node.cc(2437,5):  error: jump from this goto statement to its label is a Microsoft extension [-Werror,-Wmicrosoft-goto]
    goto out;
    ^
src/node.cc(2441,9):  note: jump bypasses variable initialization
  DWORD pid = args[0].As<Integer>()->Value();
        ^
```

PR-URL: #22961
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Denys Otrishko <shishugi@gmail.com>
Reviewed-By: Tobias Nießen <tniessen@tnie.de>
Reviewed-By: Richard Lau <riclau@uk.ibm.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Joyee Cheung <joyeec9h3@gmail.com>

src/node.cc

@@ -2278,14 +2278,15 @@ static void DebugProcess(const FunctionCallbackInfo<Value>& args) {
   HANDLE mapping = nullptr;
   wchar_t mapping_name[32];
   LPTHREAD_START_ROUTINE* handler = nullptr;
+  DWORD pid = 0;
 
   if (args.Length() != 1) {
     env->ThrowError("Invalid number of arguments.");
     goto out;
   }
 
   CHECK(args[0]->IsNumber());
-  DWORD pid = args[0].As<Integer>()->Value();
+  pid = args[0].As<Integer>()->Value();
 
   process = OpenProcess(PROCESS_CREATE_THREAD | PROCESS_QUERY_INFORMATION |
                             PROCESS_VM_OPERATION | PROCESS_VM_WRITE |