remove dependency on kernel headers for arm-linux build

[Nick Clifton]

Hi Philip,

> >The problem with this patch (which I have been tempted to submit
> >several times) is that it assumes that the constants in asm/unistd.h
> >for ARM/Linux will have (and have not) changed.
> 
> I don't think this is a problem.  Realistically, those constants
> can't ever be changed as this would break all existing binaries.

Well in that case I would say "go for it" :-)

Cheers
        Nick