Update miscellaneous files from upstream sources.

This patch updates some miscellaneous files from their upstream
sources (thereby bringing in copyright date updates for some of those
files).

Tested for x86_64, including "make pdf".

	* manual/texinfo.tex: Update to version 2018-12-28.17 with
	trailing whitespace removed.
	* scripts/config.guess: Update to version 2019-01-01.
	* scripts/config.sub: Update to version 2019-01-01.
	* scripts/move-if-change: Update from gnulib.