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/Makefile.am, add
lib/libbison.a so gnulib libraries can be linked.
(cherry picked from commit 5c99151aeb)

Conflicts:

	lib/.cvsignore
	lib/.gitignore
	m4/.cvsignore
	m4/.gitignore

lib/.cvsignore

@@ -1,8 +1,11 @@
 .deps
 Makefile
 Makefile.in
+alloca.in.h
 argmatch.c
 argmatch.h
+asnprintf.c
+basename-lgpl.c
 basename.c
 bitrotate.h
 c-ctype.c
@@ -15,16 +18,27 @@ config.charset
 config.h
 config.hin
 configmake.h
+dirname-lgpl.c
 dirname.c
 dirname.h
 dup-safer.c
+dup2.c
 errno.in.h
 error.c
 error.h
 exitfail.c
 exitfail.h
 fd-safer.c
+float+.h
+float.in.h
 fopen-safer.c
+fopen.c
+fprintf.c
+fpucw.h
+frexp.c
+frexpl.c
+fseterr.c
+fseterr.h
 getopt.c
 getopt.h
 getopt.in.h
@@ -40,9 +54,17 @@ intprops.h
 inttypes.h
 inttypes.in.h
 inttypes_.h
+isnan.c
+isnand-nolibm.h
+isnand.c
+isnanf-nolibm.h
+isnanf.c
+isnanl-nolibm.h
+isnanl.c
 localcharset.c
 localcharset.h
 malloc.c
+math.in.h
 mbrtowc.c
 mbsinit.c
 mbswidth.c
@@ -52,14 +74,30 @@ memchr.valgrind
 obstack.c
 obstack.h
 pipe-safer.c
+printf-args.c
+printf-args.h
+printf-frexp.c
+printf-frexp.h
+printf-frexpl.c
+printf-frexpl.h
+printf-parse.c
+printf-parse.h
+printf.c
 quote.c
 quote.h
 quotearg.c
 quotearg.h
+realloc.c
 ref-add.sed
 ref-add.sin
 ref-del.sed
 ref-del.sin
+signbitd.c
+signbitf.c
+signbitl.c
+size_max.h
+snprintf.c
+sprintf.c
 stamp-h1
 stdbool.h
 stdbool.in.h
@@ -69,7 +107,10 @@ stdint.h
 stdint.in.h
 stdint_.h
 stdio--.h
+stdio-impl.h
 stdio-safer.h
+stdio-write.c
+stdio.in.h
 stdlib.h
 stdlib.in.h
 stdlib_.h
@@ -96,7 +137,12 @@ uniwidth
 uniwidth.h
 unlocked-io.h
 unsetenv.c
+vasnprintf.c
+vasnprintf.h
 verify.h
+vfprintf.c
+vsnprintf.c
+vsprintf.c
 wchar.h
 wchar.in.h
 wchar_.h
@@ -108,5 +154,6 @@ wcwidth.h
 xalloc-die.c
 xalloc.h
 xmalloc.c
+xsize.h
 xstrndup.c
 xstrndup.h