bug#12477: undefined reference for scm_init_popen

[lin ray]

I got an undefined reference for scm_init_popen when I complied guile 2.0.6
on Windows, the scm_init_popen functions is introduced as following in the
posix.c

#ifdef HAVE_FORK
static void
scm_init_popen (void)
{
  scm_c_define_gsubr ("open-process", 2, 0, 1, scm_open_process);
}
#endif

since FORK is unavaiable in Windows, so the belowing part in posix.c should
be error.

  scm_c_register_extension ("libguile-" SCM_EFFECTIVE_VERSION,
                            "scm_init_popen",
       (scm_t_extension_init_func) scm_init_popen,
       NULL);


Regards
Ray Linn