The configuration file at the moment only contains the CMSIS NVIC
virtualization macros. When FEATURE_UVISOR is set, we turn on CMSIS NVIC
virtualization automatically.
This removes the need for users to specify the macros themselves.
If UVISOR_SUPPORTED is set as well, the NVIC macros are turned into vIRQ
ones, otherwise they stay NVIC as usual, thanks to the fallback
implementation provided by `unsupported.h`.
Alessandro Angelino