For a threadsafe newlib C implementation, we need to define:
FreeRTOSConfig.h
#define configUSE_NEWLIB_REENTRANT 1
and provide reentrant implementations for sbrk(), malloc_lock(), malloc_unlock(), env_lock(), env_unlock(). Broadly used is this independent implementation: newlib and FreeRTOS.
To use this implementation, we have to exclude the libc_mem_support from the libc_support component.