4.2 source compatibility

[Guy Harris]

> I really like to try to keep my source code generic, with the
> occasional machine/compiler/operating dependencies handled with
> #ifdef's.  This is more-or-less possible in all cases I have come
> across except for the stupid .h files that moved under 4.2.  (I
> refer specifically to time.h and ndir.h .) ...
> 
> A PLEA TO BERKELEY (but it's probably too late for 4.3):

I believe there is a <time.h> as well as a <sys/time.h> in 4.3 (yay!).  As
for <ndir.h>, I don't know which systems other than 4.[23] are distributed
with the directory library; the maintainers of those systems should 1) put
<ndir.h> or whatever into <dir.h> and 2) put the directory library routines
into the C library.  4.3 should then make <dir.h> a symlink to <sys/dir.h>
or something like that.  (We did both at CCI - the first in our V7/S3-based
system and the second in our 4.2-based system.)

	Guy Harris