Cygwin: dll_list: query dll file id at load time

NtQueryVirtualMemory for MemorySectionName does not reliable return the
changed dll file name when another process does move the file around,
and we may end up creating forkable hardlinks to wrong dll files.
So query the file id when loading the dll rather than before fork.

winsup/cygwin/dll_init.cc

@@ -380,6 +380,8 @@ dll_list::alloc (HINSTANCE h, per_process *p, dll_type type)
 	  d->forkable_ntname = d->ntname + ntnamelen + 1;
 	  *d->forkable_ntname = L'\0';
 	}
+      if (forkables_supported ())
+	d->stat_real_file_once (); /* uses nt_max_path_buf () */
       append (d);
       if (type == DLL_LOAD)
 	loaded_dlls++;

winsup/cygwin/forkable.cc

@@ -605,10 +605,6 @@ dll_list::forkable_ntnamesize (dll_type type, PCWCHAR fullntname, PCWCHAR modnam
 void
 dll_list::prepare_forkables_nomination ()
 {
-  dll *d = &dlls.start;
-  while ((d = d->next))
-    d->stat_real_file_once (); /* uses nt_max_path_buf () */
-
   PWCHAR pbuf = nt_max_path_buf ();
 
   bool needsep = false;