Plug a long standing leak in libtls CRL handling

X509_STORE_add_crl() does not take ownership of the CRL, it bumps its
refcount. So nulling out the CRL from the stack will leak it.

Issue reported by KS Sreeram, thanks!

ok jsing

Author: tb

src/lib/libtls/tls.c

@@ -1,4 +1,4 @@
-/* $OpenBSD: tls.c,v 1.92 2021/10/21 14:31:21 tb Exp $ */
+/* $OpenBSD: tls.c,v 1.93 2022/01/25 21:51:24 eric Exp $ */
 /*
  * Copyright (c) 2014 Joel Sing <jsing@openbsd.org>
  *
@@ -647,7 +647,6 @@ tls_configure_ssl_verify(struct tls *ctx, SSL_CTX *ssl_ctx, int verify)
 				tls_set_error(ctx, "failed to add crl");
 				goto err;
 			}
-			xi->crl = NULL;
 		}
 		X509_STORE_set_flags(store,
 		    X509_V_FLAG_CRL_CHECK | X509_V_FLAG_CRL_CHECK_ALL);