readlink: update for relocatable

[Bruno Haible]

Likewise for 'readlink':

2007-03-03  Bruno Haible  <address@hidden>

        * m4/readlink.m4 (gl_FUNC_READLINK_SEPARATE): New macro.
        (gl_FUNC_READLINK): Update.

*** m4/readlink.m4      19 Feb 2007 02:24:42 -0000      1.4
--- m4/readlink.m4      3 Mar 2007 19:29:51 -0000
***************
*** 1,4 ****
! # readlink.m4 serial 3
  dnl Copyright (C) 2003, 2007 Free Software Foundation, Inc.
  dnl This file is free software; the Free Software Foundation
  dnl gives unlimited permission to copy and/or distribute it,
--- 1,4 ----
! # readlink.m4 serial 4
  dnl Copyright (C) 2003, 2007 Free Software Foundation, Inc.
  dnl This file is free software; the Free Software Foundation
  dnl gives unlimited permission to copy and/or distribute it,
***************
*** 7,13 ****
  AC_DEFUN([gl_FUNC_READLINK],
  [
    AC_REQUIRE([gl_UNISTD_H_DEFAULTS])
!   AC_CHECK_FUNCS(readlink)
    if test $ac_cv_func_readlink = no; then
      HAVE_READLINK=0
      AC_LIBOBJ(readlink)
--- 7,13 ----
  AC_DEFUN([gl_FUNC_READLINK],
  [
    AC_REQUIRE([gl_UNISTD_H_DEFAULTS])
!   AC_CHECK_FUNCS_ONCE([readlink])
    if test $ac_cv_func_readlink = no; then
      HAVE_READLINK=0
      AC_LIBOBJ(readlink)
***************
*** 15,20 ****
--- 15,27 ----
    fi
  ])
  
+ # Like gl_FUNC_READLINK, except prepare for separate compilation (no 
AC_LIBOBJ).
+ AC_DEFUN([gl_FUNC_READLINK_SEPARATE],
+ [
+   AC_CHECK_FUNCS_ONCE([readlink])
+   gl_PREREQ_READLINK
+ ])
+ 
  # Prerequisites of lib/readlink.c.
  AC_DEFUN([gl_PREREQ_READLINK],
  [