syntax-check, update bootstrap, update gnulib

[Jim Meyering]

Here's a heads-up, so no one wastes time duplicating the not-insignificant
effort of updating to both the latest bootstrap and the latest gnulib.
The ChangeLog entries of the later commits are not complete, but "make
distcheck" does pass.

I've left the update-gnulib commit separate from the two following ones
that first make "make check" pass, and then make quoting more consistent.
There are doubtless a few more places where quoting can be adjusted to
conform to the new style, but for now, I'll stop with this series.

On the other hand, "make syntax-check" has been failing for some time,
and the first few changes address some of those failures.

Joel, if you now agree to the use gitlog-to-changelog (with --no-clump),
let me know and I'll add it and adapt this series not to update the
ChangeLog file.

Oh, also, I'll refresh the "update to gnulib" commit to use
the latest, rather than what was the latest when I wrote that.

[01/11] doc: correct typo: s/can not/cannot/
[02/11] maint: get gpl-3.0 from gnulib
[03/11] maint: remove final trailing space
[04/11] maint: placate the space-TAB syntax-check
[05/11] maint: list djgpp/subpipe.c in po/POTFILES.in
[06/11] build: include <config.h> from lib/yyerror.c
[07/11] maint: include <config.h> first
[08/11] build: manually update bootstrap from gnulib, and
[09/11] build: update gnulib submodule to latest
[10/11] quote consistently and make tests pass with new
[11/11] change more quotes in source, and adjust tests to