LynxOS 4.0.0 has snprintf (without declaration) but no vsnprintf.

LynxOS 4.0.0 has snprintf (without declaration) but no vsnprintf.

* configure.ac: Check for vsnprintf.
* src/include/lib.h: Handle `NEED_DECLARATION_VSNPRINTF' and
`HAVE_VSNPRINTF'.
* src/include/config.hin: Regenerated.

* aclocal.m4: Updated syntax to autoconf 2.59.
(GROFF_HTML_PROGRAMS): Use AC_FOREACH.
Don't check for gsos2.
(GROFF_SRCDIR, GROFF_BUILDDIR): Removed.  autoconf 2.59 provides
working abs_top_srcdir and abs_top_builddir.

* configure.ac: Updated syntax to autoconf 2.59.
Don't call GROFF_SRCDIR and GROFF_BUILDDIR.
Replace call to AC_DECL_SYS_SIGLIST with call to AC_CHECK_DECLS.
* configure: Regenerated.

* Makefile.in, doc/Makefile.in: s/@top_srcdir@/@abs_top_srcdir@/,
s/@groff_top_builddir@/@abs_top_builddir@/.

* src/roff/groff/pipeline.c (xstrsignal):
s/SYS_SIGLIST_DECLARED/HAVE_DECL_SYS_SIGLIST/.

* src/devices/grodvi/dvi.cpp (draw_dvi_printer::draw) ['a']: Always
make start angle smaller than end angle to circumvent a bug in tpic
handling of some versions of dvipdfm (and dvipdfmx).