HAL_UARTEx_(Enable|Disable)ClockStopMode not always defined

[fpistm]

Forum user report a warning about HAL_UARTEx_(Enable|Disable)ClockStopMode which are not defined for STM32L4R5ZI, see:
http://stm32duino.com/viewtopic.php?f=48&t=3875&p=47462#p47396

"C:\Users\leigh\AppData\Local\Arduino15\packages\STM32\hardware\stm32\1.3.0\cores\arduino\stm32\uart.c: In function 'uart_init':

C:\Users\leigh\AppData\Local\Arduino15\packages\STM32\hardware\stm32\1.3.0\cores\arduino\stm32\uart.c:317:7: warning: implicit declaration of function 'HAL_UARTEx_EnableClockStopMode' [-Wimplicit-function-declaration]

HAL_UARTEx_EnableClockStopMode(huart);

^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

C:\Users\leigh\AppData\Local\Arduino15\packages\STM32\hardware\stm32\1.3.0\cores\arduino\stm32\uart.c:320:7: warning: implicit declaration of function 'HAL_UARTEx_DisableClockStopMode' [-Wimplicit-function-declaration]

HAL_UARTEx_DisableClockStopMode(huart);

^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~"

Those functions are defined only when USART_CR3_UCESM is defined:
https://github.com/stm32duino/Arduino_Core_STM32/blob/master/system/Drivers/STM32L4xx_HAL_Driver/Inc/stm32l4xx_hal_uart_ex.h#L188