Fallout from the new bootstrap.

* .gitignore: Commit sorting done by bootstrap.
* build-aux/.gitignore: Likewise.
* po/.gitignore: Likewise.

Copy the latest gnulib bootstrap, which runs autoreconf and
generates po/Makevars for us.  Other improvements include some
improved prerequisite tool checking.

This also fixes a bug in the .pot files, regarding the copyright holder.

* bootstrap: Update to version in .gnulib/build-aux.
* bootstrap.conf (MSGID_BUGS_ADDRESS, COPYRIGHT_HOLDER, SKIP_PO)
(gnulib_mk, ACLOCAL, bootstrap_epilogue): Provide overrides.
* autogen.sh (autoreconf): Avoid redundant autoreconf if bootstrap
was run.
* po/Makevars: Delete, now that bootstrap creates it.
* po/.gitignore: Update.

* Makefile.maint (sync-vcs-ignore-files): New target.
Prompted by a patch from James Morris.
http://thread.gmane.org/gmane.comp.emulators.libvirt/8619/focus=8773
Add all (now-generated) .gitignore files.
* .gitignore: New file.
* build-aux/.gitignore: New file.
* docs/.gitignore: New file.
* docs/devhelp/.gitignore: New file.
* docs/examples/.gitignore: New file.
* docs/examples/python/.gitignore: New file.
* gnulib/lib/.gitignore: New file.
* gnulib/lib/arpa/.gitignore: New file.
* gnulib/lib/netinet/.gitignore: New file.
* gnulib/lib/sys/.gitignore: New file.
* gnulib/tests/.gitignore: New file.
* include/.gitignore: New file.
* include/libvirt/.gitignore: New file.
* po/.gitignore: New file.
* proxy/.gitignore: New file.
* python/.gitignore: New file.
* python/tests/.gitignore: New file.
* qemud/.gitignore: New file.
* src/.gitignore: New file.
* tests/.gitignore: New file.
* tests/confdata/.gitignore: New file.
* tests/sexpr2xmldata/.gitignore: New file.
* tests/virshdata/.gitignore: New file.
* tests/xencapsdata/.gitignore: New file.
* tests/xmconfigdata/.gitignore: New file.
* tests/xml2sexprdata/.gitignore: New file.