Import new gnulib.

m4/vsnprintf.m4

@@ -1,9 +1,13 @@
-# vsnprintf.m4 serial 5
-dnl Copyright (C) 2002-2004, 2007-2010 Free Software Foundation, Inc.
+# vsnprintf.m4 serial 6
+dnl Copyright (C) 2002-2004, 2007-2013 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
 
+dnl Libintl 0.17 will replace vsnprintf only if it does not support %1$s,
+dnl but defers to any gnulib vsnprintf replacements.  Therefore, gnulib
+dnl must guarantee that the decision for replacing vsnprintf is a superset
+dnl of the reasons checked by libintl.
 AC_DEFUN([gl_FUNC_VSNPRINTF],
 [
   AC_REQUIRE([gl_STDIO_H_DEFAULTS])
@@ -13,7 +17,17 @@ AC_DEFUN([gl_FUNC_VSNPRINTF],
     gl_SNPRINTF_SIZE1
     case "$gl_cv_func_snprintf_size1" in
       *yes)
-        gl_cv_func_vsnprintf_usable=yes
+        gl_SNPRINTF_RETVAL_C99
+        case "$gl_cv_func_snprintf_retval_c99" in
+          *yes)
+            gl_PRINTF_POSITIONS
+            case "$gl_cv_func_printf_positions" in
+              *yes)
+                gl_cv_func_vsnprintf_usable=yes
+                ;;
+            esac
+            ;;
+        esac
         ;;
     esac
   fi