Makefile: Disable -Wreturn-type for selfie.c due to noreturn exit
Makefile: Disable -Wreturn-type for selfie.c due to noreturn exit

Due to building the kernel in freestanding mode, the compiler will use
selfie's declaration of function exit as-is. Unfortunately, this means
that the function is not annotated as noreturn function, thus the
compiler emits warnings of missing return values when there's no return
value after a exit call.

ChristianMoesl/selfie,cksystemsteaching/selfie,cksystemsteaching/selfie,cksystemsteaching/selfie,ChristianMoesl/selfie