updated gnulib

gl/m4/dup2.m4

@@ -1,4 +1,4 @@
-#serial 19
+#serial 20
 dnl Copyright (C) 2002, 2005, 2007, 2009-2013 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -39,9 +39,11 @@ AC_DEFUN([gl_FUNC_DUP2],
             /* Many gnulib modules require POSIX conformance of EBADF.  */
             if (dup2 (2, 1000000) == -1 && errno != EBADF)
               result |= 16;
-            /* Flush out a cygwin core dump.  */
+            /* Flush out some cygwin core dumps.  */
             if (dup2 (2, -1) != -1 || errno != EBADF)
               result |= 32;
+            dup2 (2, 255);
+            dup2 (2, 256);
             return result;
            ])
         ],
@@ -65,6 +67,7 @@ AC_DEFUN([gl_FUNC_DUP2],
       *yes) ;;
       *)
         REPLACE_DUP2=1
+        AC_CHECK_FUNCS([setdtablesize])
         ;;
     esac
   fi