Build fail with IAR toolchain for rtos tests [report__2016-05-11_14.45.44.48__NUCLEO-F746ZG__rtos__ALL.html.zip](https://github.com/mbedmicro/mbed/files/261476/report__2016-05-11_14.45.44.48__NUCLEO-F746ZG__rtos__ALL.html.zip)