QUIC: fixed removal of unused client IDs. If client ID was never used, its refcount is zero. To keep things simple, the ngx_quic_unref_client_id() function is now aware of such IDs. If client ID was used, the ngx_quic_replace_retired_client_id() function is supposed to find all users and unref the ID, thus ngx_quic_unref_client_id() should not be called after it.

# Copyright (C) Igor Sysoev
# Copyright (C) Nginx, Inc.


    cat << END                                            >> $NGX_MAKEFILE

$NGX_LIBATOMIC/src/libatomic_ops.a:	$NGX_LIBATOMIC/Makefile
	cd $NGX_LIBATOMIC && \$(MAKE)

$NGX_LIBATOMIC/Makefile:	$NGX_MAKEFILE
	cd $NGX_LIBATOMIC \\
	&& if [ -f Makefile ]; then \$(MAKE) distclean; fi \\
	&& ./configure

END