logging: Wrap thread local buffer initialization in a function

resolves a crash on RPi

src/debug.cpp

@@ -349,8 +349,6 @@ void debug_file_dump(const char *key, void (*serialize)(const void *data, FILE *
 
 thread_local std::set<uint32_t> Logger::oneshot_messages;
 
-thread_local std::string Log_output::buffer(initial_buf_size, '\0');
-
 Log_output::Log_output(){
         last_msg.reserve(initial_buf_size);
         interactive = color_output_init();