[Rd] Outdated information in regex.Rd

[Martin Maechler]

>>>>> Mikko Korpela <mikko.korpela at aalto.fi>
>>>>>     on Wed, 18 Nov 2015 11:35:14 +0200 writes:

    > The NEWS for R-devel has the following item:
    >> The previously included versions of zlib, bzip2, xz and PCRE have
    >> been removed, so suitable external (usually system) versions are
    >> required (see the ‘R Installation and Administration’ manual).

    > Therefore I believe the following information in
    > 'src/library/base/man/regex.Rd' is no longer valid:

    >> If PCRE support was compiled from the sources within R, the PCRE
    >> version is 8.36 as described here.

Not quite.  It is still *valid* : every statement about the
elements of the empty set are true, in the same sense that

   if (FALSE)
     "something or other"

is never invalid, but of course, that information should still
be removed because indeed, it is empty.

Thank you Mikko!
      	  (and excuse the completely unnecessary pickyness ;-)