Update miscellaneous files from upstream sources.

This patch updates various miscellaneous files from their upstream
sources.

Tested for x86_64, including "make pdf".

	* manual/texinfo.tex: Update to version 2017-12-18.20 with
	trailing whitespace removed.
	* scripts/config.guess: Update to version 2017-12-17.
	* scripts/config.sub: Update to version 2017-11-23.
	* scripts/install-sh: Update to version 2017-09-23.17.
	* scripts/move-if-change: Update to version 2017-09-13 06:45.