Conflict with MTP

[Alan-NTHU]

if choosen board Teensy 4.1/3.2/3.6/LC with "MTP experimental", the simple examples cannot compile. Choosing "serial" had no problem

it will face some conflict error as :

arduino-1.8.19\hardware\teensy\avr\libraries\Snooze\src/hal/TEENSY_LC/SnoozeUSBSerial.h:59:39: error: 'usb_cdc_line_rtsdtr' was not declared in this scope
         return usb_configuration && ( usb_cdc_line_rtsdtr & USB_SERIAL_DTR ) && ( ( uint32_t )( systick_millis_count - usb_cdc_line_rtsdtr_millis ) >= 15 );
                                       ^
arduino-1.8.19\hardware\teensy\avr\libraries\Snooze\src/hal/TEENSY_LC/SnoozeUSBSerial.h:59:61: error: 'USB_SERIAL_DTR' was not declared in this scope
         return usb_configuration && ( usb_cdc_line_rtsdtr & USB_SERIAL_DTR ) && ( ( uint32_t )( systick_millis_count - usb_cdc_line_rtsdtr_millis ) >= 15 );
                                                             ^
arduino-1.8.19\hardware\teensy\avr\libraries\Snooze\src/hal/TEENSY_LC/SnoozeUSBSerial.h:59:120: error: 'usb_cdc_line_rtsdtr_millis' was not declared in this scope
         return usb_configuration && ( usb_cdc_line_rtsdtr & USB_SERIAL_DTR ) && ( ( uint32_t )( systick_millis_count - usb_cdc_line_rtsdtr_millis ) >= 15 );

which is the three thing below undeclared,
usb_cdc_line_rtsdtr_millis;USB_SERIAL_DTR;usb_cdc_line_rtsdtr;

it seems like something in the core file "usb_desc.h" chosen by "MTP" leads to some USB undeclared and thus the USB or (SnoozeUSBSerial usb) cannot be created.