(committing libc fixes authored 29th May)
avr-libc:
        * libc/stdlib/atexit.c: New file.
        * libc/stdlib/getenv.c, libc/stdlib/system.c: Likewise.
        * libc/stdlib/Files.am (stdlib_a_c_sources): Add new files.
	* libc/include/errno.h (ENOSYS): Define.
ld:
	* scripttempl/avr.sc (SECTIONS): Add / KEEP .fini6a .