Allows bootstrap to work on FreeBSD, where gzip doesn't have a '.'
in its version; and silences false positives in the new
'make syntax-check' rule.

* .gnulib: Update to latest.
* bootstrap: Synchronize to upstream.
* .x-sc_bindtextdomain: New exemptions.
* Makefile.am (syntax_check_exceptions): Ship new file.
* .gitignore: Regenerate per latest bootstrap, anchor entries that
are only in the root directory, and consolidate entries from other
generated .gitignore files.
* build-aux/.gitignore, m4/.gitignore, po/.gitignore: Remove from
version control, since bootstrap generates them.