Implement a STATIC_ASSERT macro for uVisor

[Patater]

We currently need a STATIC_ASSERT macro to catch errors at compile time. The macro should produce very user friendly output; implementations that have cryptic error messages are unacceptable. The macro implementation must also work from both inside and outside of function scope.

[ciarmcom]

ARM Internal Ref: IOTSFW-2804

[fangyi-zhou]

http://en.cppreference.com/w/c/language/_Static_assert

[Patater]

Fixed via #478