*printf-posix: Disable support for the 'n' directive by default.

* m4/printf-with-n-directive.m4: New file.
* modules/printf-with-n-directive: New file.
* m4/dprintf-posix.m4 (gl_FUNC_DPRINTF_IS_POSIX): If
gl_PRINTF_SUPPORT_N_DIRECTIVE is not defined, ignore the value of the
gl_cv_func_printf_directive_n variable.
* m4/fprintf-posix.m4 (gl_FUNC_FPRINTF_IS_POSIX): Likewise.
* m4/obstack-printf-posix.m4 (gl_FUNC_OBSTACK_PRINTF_IS_POSIX): Likewise.
* m4/sprintf-posix.m4 (gl_FUNC_SPRINTF_IS_POSIX): Likewise.
* m4/vasnprintf-posix.m4 (gl_FUNC_VASNPRINTF_IS_POSIX): Likewise.
* m4/vasprintf-posix.m4 (gl_FUNC_VASPRINTF_IS_POSIX): Likewise.
* m4/vdprintf-posix.m4 (gl_FUNC_VDPRINTF_IS_POSIX): Likewise.
* m4/vfprintf-posix.m4 (gl_FUNC_VFPRINTF_IS_POSIX): Likewise.
* m4/vsprintf-posix.m4 (gl_FUNC_VSPRINTF_IS_POSIX): Likewise.
* m4/snprintf-posix.m4 (gl_FUNC_SNPRINTF_IS_POSIX): If
gl_PRINTF_SUPPORT_N_DIRECTIVE is not defined, ignore the values of the
gl_cv_func_printf_directive_n and gl_cv_func_snprintf_directive_n
variables.
* m4/vsnprintf-posix.m4 (gl_FUNC_VSNPRINTF_IS_POSIX): Likewise.
* lib/printf-parse.c (PRINTF_PARSE): If NEED_PRINTF_WITH_N_DIRECTIVE is
not defined, treat the 'n' directive like an unknown directive.
* lib/vasnprintf.c (VASNPRINTF): If NEED_PRINTF_WITH_N_DIRECTIVE is not
defined, disable the processing of the 'n' directive.
* tests/test-snprintf-posix.h (test_function): If
NEED_PRINTF_WITH_N_DIRECTIVE is not defined, skip the %n test.
* tests/test-sprintf-posix.h (test_function): Likewise.
* tests/test-vasnprintf-posix.c (test_function): Likewise.
* tests/test-vasnwprintf-posix.c (test_function): Likewise.
* tests/test-vasprintf-posix.c (test_function): Likewise.
* doc/posix-functions/dprintf.texi: Mention that support for the 'n'
directive is only enabled together with the module
'printf-with-n-directive'.
* doc/posix-functions/fprintf.texi: Likewise.
* doc/posix-functions/printf.texi: Likewise.
* doc/posix-functions/snprintf.texi: Likewise.
* doc/posix-functions/sprintf.texi: Likewise.
* doc/posix-functions/vdprintf.texi: Likewise.
* doc/posix-functions/vfprintf.texi: Likewise.
* doc/posix-functions/vprintf.texi: Likewise.
* doc/posix-functions/vsnprintf.texi: Likewise.
* doc/posix-functions/vsprintf.texi: Likewise.
* doc/glibc-functions/obstack_printf.texi: Likewise.
* doc/glibc-functions/obstack_vprintf.texi: Likewise.
* NEWS: Mention the change.

modules/printf-with-n-directive

@@ -0,0 +1,26 @@
+Description:
+Enable processing of the %n directive in *printf functions.
+
+Comment:
+This module should not be used as a dependency from a test module,
+otherwise when this module occurs as a tests-related module, it will
+have side effects on the compilation of the 'vasnprintf' module, if
+that module occurs among the main modules in lib/.
+
+Files:
+m4/printf-with-n-directive.m4
+
+Depends-on:
+
+configure.ac:
+gl_PRINTF_SUPPORT_N_DIRECTIVE
+
+Makefile.am:
+
+Include:
+
+License:
+LGPLv2+
+
+Maintainer:
+all