rah@rah-VirtualBox:~/mbed/mbed-nrf51-gcc-test/projects/BLE_HeartRate/Build$ ls
CMakeCache.txt  CMakeFiles  cmake_install.cmake  Makefile
rah@rah-VirtualBox:~/mbed/mbed-nrf51-gcc-test/projects/BLE_HeartRate/Build$ make
Scanning dependencies of target BLE_HEART_RATE.elf
[  1%] Building CXX object CMakeFiles/BLE_HEART_RATE.elf.dir/main.cpp.o
In file included from /home/rah/mbed/mbed-nrf51-gcc-test/projects/BLE_HeartRate/../../mbed-src/libraries/mbed/api/mbed.h:21:0,
                 from /home/rah/mbed/mbed-nrf51-gcc-test/projects/BLE_HeartRate/main.cpp:17:
/home/rah/mbed/mbed-nrf51-gcc-test/projects/BLE_HeartRate/../../mbed-src/libraries/mbed/api/platform.h:25:19: fatal error: cstddef: No such file or directory
 #include <cstddef>
                   ^
compilation terminated.
make[2]: *** [CMakeFiles/BLE_HEART_RATE.elf.dir/main.cpp.o] Error 1
make[1]: *** [CMakeFiles/BLE_HEART_RATE.elf.dir/all] Error 2
make: *** [all] Error 2