config: Add lock/unlock macro for no multithreading

#if ((defined(__SES_ARM) || defined(__SES_RISCV) || defined(__CROSSWORKS_ARM) || defined(__GNUC__) || defined(__clang__)) && !defined (__CC_ARM) && !defined(WIN32))

  #if defined(__ZEPHYR__) && defined (CONFIG_SEGGER_RTT_CUSTOM_LOCKING)

    #include <kernel.h>

    #ifdef CONFIG_MULTITHREADING

      extern struct k_mutex rtt_term_mutex;

      #define SEGGER_RTT_LOCK() k_mutex_lock(&rtt_term_mutex, K_FOREVER);

      #define SEGGER_RTT_UNLOCK() k_mutex_unlock(&rtt_term_mutex);

    #else

      #define SEGGER_RTT_LOCK() { \

        unsigned int key = irq_lock()

      #define SEGGER_RTT_UNLOCK() irq_unlock(key); \

        }

    #endif

    #define RTT_USE_ASM 0

  #elif (defined(__ARM_ARCH_6M__) || defined(__ARM_ARCH_8M_BASE__))

    #define SEGGER_RTT_LOCK()   {                                                                   \