3rd-party/segger-rtt:: allow for sys functions to be overwritten
3rd-party/segger-rtt: update to V786a
segger-rtt: set default to no block skip mode
stm32-wb55-nucleo-freertos port
segger-rtt: add SEGGER_RTT_GetAvailWriteSpace function
segger-rtt: update to v6.54, document modifications for BTstack
segger-rtt: fix compile for arm-none-eabi-gcc
segger-rtt: add rtt files