Re-use parent console if it's available

* This means we won't get an ugly console window popping up when running
  renderdoccmd on windows, but if we run it from a terminal then we'll
  get output as normal.
* One downside is that cmd.exe seems to snoop the exe type (GUI or
  console) and if it's a GUI application it returns to the prompt
  immediately. bash for example though waits for process termination.
* The other is that pipe redirects to file don't work properly.

Author: baldurk

renderdoccmd/renderdoccmd_win32.cpp

@@ -808,6 +808,15 @@ int WINAPI wWinMain(_In_ HINSTANCE hInst, _In_opt_ HINSTANCE hPrevInstance, _In_
   LPWSTR *wargv;
   int argc;
 
+  if(AttachConsole(ATTACH_PARENT_PROCESS))
+  {
+    freopen("CONOUT$", "w", stdout);
+    freopen("CONOUT$", "w", stderr);
+
+    std::cout.sync_with_stdio();
+    std::cerr.sync_with_stdio();
+  }
+
   wargv = CommandLineToArgvW(GetCommandLine(), &argc);
 
   std::vector<std::string> argv;