Minor improvements in a few files.
Updates to .gitignore.
VMS doc updates.
Bug fix to do_split().
Remove vms/vms-notes file before making test dist.
Update version for test tarball.
Make 'system' and pipe writes consistent with pipe reads on MinGW.

* popen.c (os_system): Use spawnl, and quote the command line, to
be consistent with what gawk_popen does.
(os_popen) [__MINGW32__]: Don't scriptify the command, to be
consistent with gawk_popen.
(os_pclose) [__MINGW32__]: Update to match os_open: no need to
unlink the script file.
Fix pc/Makefile.tst per the changes in the test suite.

* pc/Makefile.tst (mbprintf4, profile5, backbigs1, backsmalls1):
Announce expected failures.
(fts): Fail gracefully, to avoid bailing out of the test suite too
early.
Fix strftime test race condition.
Configure fixes for z/OS.
Add split_after_fpat test for VMS.
Updated fi, fr, it, vi translations.
Quote $(top_srcdir) in test/Makefile.am.
Fix typo from last change.
Update dfa.c:parse_bracket_exp.
Update nl translation.
Fix -0 for MPFR.