Move copybs to dosutil, change the Makefile to deal with UPX being
able to compress (e.g. very small files.)

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

Resolved Conflicts:
	com32/Makefile
	com32/lib/sys/open.c
	com32/modules/Makefile
	dos/Makefile
	dos/com16.ld
	dos/syslinux.c
	version

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

int 25h and int 26h are known to be register-dirty for some versions
of DOS -- unlike int 21h, which is usually clean.  As such, wrap those
in assembly functions.

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

My version of the linker can deal with it, but others might not be so
smart.

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

gcc will produce an .eh_frame section, which we have no use for.

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

At least under WinME, the DOS installer did not work as advertised.
With these modifications, it seems to work okay.

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

Assume NASM 2.03 or later, so use -MP -MD to generate dependencies.

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

You'd think upx --ultra-brute would test everything that is possible,
but not so.  --lzma needs to be specified separately.

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

If UPX is installed on the host system, we might as well use it to
compress the DOS installer binary.

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