this is not a question but a hint for those who are also struggling building cpp files.
I always got the error message "undefined reference to application_start" when I wanted to compile a cpp file for a the platform BCM4343W_AVN.
I solved it with adding extern void application_start(void); in the file 43xxx_Wi-Fi/include/wiced_rtos.h
maybe one of the developers sees this and adds this in the next release.
Thanks for bringing it to our notice. I will pass your suggestion along to the developers.