ControllerInterface: Add synchronisation

Since we may have to add/access devices from different threads, this
adds synchronisation to anything that touches m_devices.

Source/Core/InputCommon/ControllerInterface/ControllerInterface.cpp

@@ -104,6 +104,8 @@ void ControllerInterface::Shutdown()
   if (!m_is_init)
     return;
 
+  std::lock_guard<std::mutex> lk(m_devices_mutex);
+
   for (ciface::Core::Device* d : m_devices)
   {
     // Set outputs to ZERO before destroying device
@@ -141,6 +143,7 @@ void ControllerInterface::Shutdown()
 
 void ControllerInterface::AddDevice(ciface::Core::Device* device)
 {
+  std::lock_guard<std::mutex> lk(m_devices_mutex);
   m_devices.push_back(device);
 }
 
@@ -151,6 +154,7 @@ void ControllerInterface::AddDevice(ciface::Core::Device* device)
 //
 void ControllerInterface::UpdateInput()
 {
+  std::lock_guard<std::mutex> lk(m_devices_mutex);
   for (ciface::Core::Device* d : m_devices)
     d->UpdateInput();
 }