@apica, first, make sure you are compiling from the "main" directory in the firmware repo. I just compiled an app with and without
#include "stm32f2xx_wwdg.h" and had no errors. I compiled with both the latest develop branch and the latest release, again without errors.
I compiled my app from the "main" directory using:
make clean all PLATFORM=photon APP=xxxxx or
make clean all PLATFORM=photon PARTICLE_DEVELOP=1 APP=xxxxx
I tested with both PLATFORM=photon and PLATFORM=electron with the same results.