5218 posix definition of NULL
correct unistd.h and iso/stddef_iso.h
update gate source affected

@@ -380,11 +380,11 @@
         char KS[16][48];
  
         for(i=0; i<66; i++)
                 block[i] = 0;
         /* Solaris Kerberos */
-        for(i=0; ((c= *pw) != NULL) && i<64; pw++){
+        for(i=0; ((c= *pw) != 0) && i<64; pw++){
                 for(j=0; j<7; j++, i++)
                         block[i] = (c>>(6-j)) & 01;
                 i++;
         }