Change to C version of startup_stm32f40xx
Add support for the RCC->PLLCFGR register for stm32f4
Initial support for PWR peripheral in emulator
Initial support for SCB peripheral in emulator
Add SCB and PWR peripherals to emulator, Temporal solution for compiling emulator for stm32f4
Enable new C startup code for stm32f4 discovery in emulator