portability: fix spawning on at least FreeBSD 8 and FreeBSD 9.

Reported by Johan van Selst at
<http://lists.gnu.org/archive/html/bug-bison/2010-03/msg00014.html>.
* NEWS (2.4.3): New.
* THANKS (Johan van Selst): Add.
* gnulib: Update to latest.

m4/.cvsignore

@@ -100,8 +100,10 @@ warn-on-use.m4
 warning.m4
 warnings.m4
 wchar.m4
+wchar_h.m4
 wchar_t.m4
 wctype.m4
+wctype_h.m4
 wcwidth.m4
 wint_t.m4
 xalloc.m4