Log Message:
Update to 3.5.3

Upstream changes:
CHANGES IN R 3.5.3:

  INSTALLATION on a UNIX-ALIKE:

    * Detection of flags for C++98/11/14/17 has been improved: in
      particular if CXX??STD is set, it is tried first with no
      additional flags.

  PACKAGE INSTALLATION:

    * New macro F_VISIBILITY as an alternative to F77_VISIBILITY.  This
      will become the preferred form in R 3.6.0.

  BUG FIXES:

    * writeLines(readLines(fnam), fnam) now works as expected, thanks
      to Peter Meissner's PR#17528.

    * setClassUnion() no longer warns, but uses message() for now, when
      encountering "non local" subclasses of class members.

    * stopifnot(exprs = T) no longer fails.