[TUHS] link() syscall implementation

[Oliver Lehmann]

I've now implemented this:

         u.u_dirp.left = hiword(uap->linkname) & 0x7f00;
         u.u_dirp.right = loword(uap->linkname);

while hiword and loword being defined in my param.h like this:

# define loword(X)      (((unsigned short *)&X)[sizeof(X) - \
                         (sizeof(unsigned short)+1)])
# define hiword(X)      (((unsigned short *)&X)[0])

This results in:

         ld      r2,rr8(#4)
         and     r2,#32512
         ld      _u+78,r2
         ld      r2,rr8(#6)
         ld      _u+80,r2


versus

         ldl        rr2,rr8(#4)
         ldl        rr4,rr2
         and        r4,#32512
         ldl        _u+78,rr4

does the same but  with more instructions and of course not 1:1
binary "the same" ;)
wonder why
   u.u_dirp.l = (caddr_t)(((long)uap->linkname) & 0x7F00FFFF);
didn't worked.

At least link() is now working again (before the fix it was only
working when the file to be linked is in the working directory)

#1 ls -i /z/tmp/
  2487 hugo   2486 walter
#2 rm /z/tmp/walter
#3 ln /z/tmp/hugo /z/tmp/walter
#4 !1
ls -i /z/tmp/
  2487 hugo   2487 walter
#5 ln /z/tmp/hugo /z/walter
#6 ls -i /z/tmp/hugo /z/walter
  2487 /z/tmp/hugo                  2487 /z/walter
#7