[PATCH] resolv: reset _u._ext.nscount in __res_iclose [BZ #34154]

[Florian Weimer]

* Adam Yi:

> diff --git a/resolv/tst-resolv-res_init-failure.c b/resolv/tst-resolv-res_init-failure.c
> new file mode 100644
> index 0000000000..6fcb028684
> --- /dev/null
> +++ b/resolv/tst-resolv-res_init-failure.c
> @@ -0,0 +1,109 @@
> +/* Test that name lookups do not crash after a failing res_init call.
> +   Copyright (C) 2026 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.

New files contributed under DCO should use the DCO copyright statement,
“Copyright The GNU Toolchain Authors.”

Analysis, fix and test look reasonable to me.  Thanks.