strfunc: always null-terminate the output buffer
strfunc: always null-terminate the output buffer

Make sure that the buffer is always null-terminated, even though we do
have to use the length, since the string can (and often will) have
embedded nulls.

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