elf: Replace nsid with args.nsid [BZ #27609]

commit ec935dea
Author: Florian Weimer <fweimer@redhat.com>
Date:   Fri Apr 24 22:31:15 2020 +0200

    elf: Implement __libc_early_init

has

@@ -856,6 +876,11 @@ no more namespaces available for dlmopen()"));
   /* See if an error occurred during loading.  */
   if (__glibc_unlikely (exception.errstring != NULL))
     {
+      /* Avoid keeping around a dangling reference to the libc.so link
+   map in case it has been cached in libc_map.  */
+      if (!args.libc_already_loaded)
+  GL(dl_ns)[nsid].libc_map = NULL;
+

do_dlopen calls _dl_open with nsid == __LM_ID_CALLER (-2), which calls
dl_open_worker with args.nsid = nsid.  dl_open_worker updates args.nsid
if it is __LM_ID_CALLER.  After dl_open_worker returns, it is wrong to
use nsid.

Replace nsid with args.nsid after dl_open_worker returns.  This fixes
BZ #27609.

(cherry picked from commit 1e1ecea6)