portability: use -DGNULIB_POSIXCHECK.

Reported by Eric Blake.  See discussions at
<http://lists.gnu.org/archive/html/bug-bison/2009-09/msg00008.html>
and
<http://lists.gnu.org/archive/html/bug-gnulib/2009-10/msg00108.html>.
* HACKING (Release checks): Suggest -DGNULIB_POSIXCHECK.
* bootstrap.conf (gnulib_modules): Add all the printf modules
suggested by -DGNULIB_POSIXCHECK.  Add realloc-posix as
suggested by -DGNULIB_POSIXCHECK for gnulib's own vasnprintf.c.
(excluded_files): Remove m4/printf-posix.m4.
* tests/atlocal.in (LIBS): As for LDADD in src/local.mk, add
lib/libbison.a so gnulib libraries can be linked.

m4/.cvsignore

@@ -1,18 +1,28 @@
 00gnulib.m4
 absolute-header.m4
+alloca.m4
 argmatch.m4
 assert.m4
 config-h.m4
 dirname.m4
 dos.m4
 double-slash-root.m4
+dup2.m4
 environ.m4
 errno_h.m4
 error.m4
 exitfail.m4
+exponentd.m4
+exponentf.m4
+exponentl.m4
 extensions.m4
 fcntl_h.m4
+float_h.m4
 fopen.m4
+fpieee.m4
+fprintf-posix.m4
+frexp.m4
+frexpl.m4
 getopt.m4
 getpagesize.m4
 gettext.m4
@@ -25,11 +35,16 @@ iconv.m4
 include_next.m4
 inline.m4
 intlmacosx.m4
+intmax_t.m4
 inttypes-h.m4
 inttypes-pri.m4
 inttypes.m4
+isnand.m4
+isnanf.m4
+isnanl.m4
 javacomp.m4
 javaexec.m4
+ldexpl.m4
 lib-ld.m4
 lib-link.m4
 lib-prefix.m4
@@ -39,6 +54,7 @@ locale-ja.m4
 locale-zh.m4
 longlong.m4
 malloc.m4
+math_h.m4
 mbrtowc.m4
 mbsinit.m4
 mbstate_t.m4
@@ -47,11 +63,22 @@ memchr.m4
 mmap-anon.m4
 multiarch.m4
 nls.m4
+nocrash.m4
 po.m4
+printf-frexp.m4
+printf-frexpl.m4
+printf-posix-rpl.m4
+printf-posix.m4
+printf.m4
 progtest.m4
 quote.m4
 quotearg.m4
+realloc.m4
 setenv.m4
+signbit.m4
+snprintf-posix.m4
+snprintf.m4
+sprintf-posix.m4
 stdbool.m4
 stddef_h.m4
 stdint.m4
@@ -71,6 +98,12 @@ threadlib.m4
 unistd-safer.m4
 unistd_h.m4
 unlocked-io.m4
+vasnprintf-posix.m4
+vasnprintf.m4
+vfprintf-posix.m4
+vsnprintf-posix.m4
+vsnprintf.m4
+vsprintf-posix.m4
 warning.m4
 warnings.m4
 wchar.m4