nasm.c: use error helpers, remove ERR_NOFILE
nasm.c: use error helpers, remove ERR_NOFILE

The current error handlers are much smarter about missing filenames,
and thus using ERR_NOFILE just makes it harder for the programmer.

Signed-off-by: H. Peter Anvin <8a453bad9912ffe59bc0f0b8abe03df9be19379e@zytor.com>

techkey/nasm,techkey/nasm,techkey/nasm,techkey/nasm,techkey/nasm