preproc.c: revamped context-local fall-through warning message
preproc.c: revamped context-local fall-through warning message

letolabs/nasm,projedi/nasm,techkey/nasm,techkey/nasm,letolabs/nasm,turingstudio/nasm,projedi/nasm,projedi/nasm,projedi/nasm,projedi/nasm,turingstudio/nasm,techkey/nasm,turingstudio/nasm,turingstudio/nasm,Distrotech/nasm,Distrotech/nasm,Distrotech/nasm,letolabs/nasm,Distrotech/nasm,techkey/nasm,techkey/nasm