Change renderdoccmd to be a console program on windows.

* This means it outputs natively/properly to stdout/stderr and its output can be
  redirected with pipes.
* It does mean we need to be very careful whenever it's run internally to not
  pop up a command window, which happens by default.

qrenderdoc/Windows/Dialogs/UpdateDialog.cpp

@@ -252,9 +252,9 @@ void UpdateDialog::on_update_clicked()
 
       QDir::setCurrent(dir.absolutePath());
 
-      success = RunProcessAsAdmin(dir.absoluteFilePath(cmd), QStringList()
-                                                                 << lit("upgrade") << lit("--path")
-                                                                 << appDir.absolutePath());
+      success = RunProcessAsAdmin(
+          dir.absoluteFilePath(cmd),
+          QStringList() << lit("upgrade") << lit("--path") << appDir.absolutePath(), NULL, true);
 
       exit(0);