Update Gnulib; add new modules; remove `round' module.

This updates Gnulib to v0.0-4951-g6ff7b70.

* m4/gnulib-cache.m4: Add floor, ceil, frexp, and ldexp.  Add wchar as
  an explicit dependency; it had been present as an indirect dependency
  before, but no longer.  Remove round, which I had requested earlier,
  but turned out to be unnecessary.

lib/stdio-write.c

@@ -1,148 +0,0 @@
-/* POSIX compatible FILE stream write function.
-   Copyright (C) 2008-2011 Free Software Foundation, Inc.
-   Written by Bruno Haible <bruno@clisp.org>, 2008.
-
-   This program is free software: you can redistribute it and/or modify
-   it under the terms of the GNU Lesser General Public License as published by
-   the Free Software Foundation; either version 3 of the License, or
-   (at your option) any later version.
-
-   This program is distributed in the hope that it will be useful,
-   but WITHOUT ANY WARRANTY; without even the implied warranty of
-   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-   GNU Lesser General Public License for more details.
-
-   You should have received a copy of the GNU Lesser General Public License
-   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
-
-#include <config.h>
-
-/* Specification.  */
-#include <stdio.h>
-
-/* Replace these functions only if module 'sigpipe' is requested.  */
-#if GNULIB_SIGPIPE
-
-/* On native Windows platforms, SIGPIPE does not exist.  When write() is
-   called on a pipe with no readers, WriteFile() fails with error
-   GetLastError() = ERROR_NO_DATA, and write() in consequence fails with
-   error EINVAL.  This write() function is at the basis of the function
-   which flushes the buffer of a FILE stream.  */
-
-# if (defined _WIN32 || defined __WIN32__) && ! defined __CYGWIN__
-
-#  include <errno.h>
-#  include <signal.h>
-#  include <io.h>
-
-#  define WIN32_LEAN_AND_MEAN  /* avoid including junk */
-#  include <windows.h>
-
-#  define CALL_WITH_SIGPIPE_EMULATION(RETTYPE, EXPRESSION, FAILED) \
-  if (ferror (stream))                                                        \
-    return (EXPRESSION);                                                      \
-  else                                                                        \
-    {                                                                         \
-      RETTYPE ret;                                                            \
-      SetLastError (0);                                                       \
-      ret = (EXPRESSION);                                                     \
-      if (FAILED && GetLastError () == ERROR_NO_DATA && ferror (stream))      \
-        {                                                                     \
-          int fd = fileno (stream);                                           \
-          if (fd >= 0                                                         \
-              && GetFileType ((HANDLE) _get_osfhandle (fd)) == FILE_TYPE_PIPE)\
-            {                                                                 \
-              /* Try to raise signal SIGPIPE.  */                             \
-              raise (SIGPIPE);                                                \
-              /* If it is currently blocked or ignored, change errno from     \
-                 EINVAL to EPIPE.  */                                         \
-              errno = EPIPE;                                                  \
-            }                                                                 \
-        }                                                                     \
-      return ret;                                                             \
-    }
-
-#  if !REPLACE_PRINTF_POSIX /* avoid collision with printf.c */
-int
-printf (const char *format, ...)
-{
-  int retval;
-  va_list args;
-
-  va_start (args, format);
-  retval = vfprintf (stdout, format, args);
-  va_end (args);
-
-  return retval;
-}
-#  endif
-
-#  if !REPLACE_FPRINTF_POSIX /* avoid collision with fprintf.c */
-int
-fprintf (FILE *stream, const char *format, ...)
-{
-  int retval;
-  va_list args;
-
-  va_start (args, format);
-  retval = vfprintf (stream, format, args);
-  va_end (args);
-
-  return retval;
-}
-#  endif
-
-#  if !REPLACE_VPRINTF_POSIX /* avoid collision with vprintf.c */
-int
-vprintf (const char *format, va_list args)
-{
-  return vfprintf (stdout, format, args);
-}
-#  endif
-
-#  if !REPLACE_VFPRINTF_POSIX /* avoid collision with vfprintf.c */
-int
-vfprintf (FILE *stream, const char *format, va_list args)
-#undef vfprintf
-{
-  CALL_WITH_SIGPIPE_EMULATION (int, vfprintf (stream, format, args), ret == EOF)
-}
-#  endif
-
-int
-putchar (int c)
-{
-  return fputc (c, stdout);
-}
-
-int
-fputc (int c, FILE *stream)
-#undef fputc
-{
-  CALL_WITH_SIGPIPE_EMULATION (int, fputc (c, stream), ret == EOF)
-}
-
-int
-fputs (const char *string, FILE *stream)
-#undef fputs
-{
-  CALL_WITH_SIGPIPE_EMULATION (int, fputs (string, stream), ret == EOF)
-}
-
-int
-puts (const char *string)
-#undef puts
-{
-  FILE *stream = stdout;
-  CALL_WITH_SIGPIPE_EMULATION (int, puts (string), ret == EOF)
-}
-
-size_t
-fwrite (const void *ptr, size_t s, size_t n, FILE *stream)
-#undef fwrite
-{
-  CALL_WITH_SIGPIPE_EMULATION (size_t, fwrite (ptr, s, n, stream), ret < n)
-}
-
-# endif
-#endif