This patch updates various files from their upstream sources. This
brings in copyright date updates for some of those files.
Tested for x86_64.
* manual/texinfo.tex: Update to version 2017-12-26.21 with
trailing whitespace removed.
* scripts/config.guess: Update to version 2018-01-01.
* scripts/config.sub: Update to version 2018-01-01.
* scripts/move-if-change: Update from gnulib.