brk does not count the data segment toward RLIMIT_DATA #487

Linux's check_data_rlimit holds (brk - start_brk) + (end_data - start_data) to the soft RLIMIT_DATA. elfuse (after #485) holds only brk - brk_base, because it does not record start_data/end_data. A break can then grow past the limit by up to the size of the data segment. A fix would record both values in the ELF loader and carry them through execve and the fork state.