2014-02-11  Joey Ye  <joey.ye@arm.com>

        * libc/sys/arm/syscalls.c (_sbrk): Define as weak symbols.
        (_read, _write): Ditto.
2014-02-11  Joey Ye  <joey.ye@arm.com>

        * arm/syscalls.c (_sbrk): Define as weak symbols.
        (_read, _write): Ditto.