BUG/MINOR: ssl/cli: don't overwrite the filters variable

When a crt-list line using an already used ckch_store does not contain
filters, it will overwrite the ckchs->filters variable with 0.
This problem will generate all sni_ctx of this ckch_store without
filters. Filters generation mustn't be allowed in any case.

Must be backported in 2.1.
diff --git a/src/ssl_sock.c b/src/ssl_sock.c
index e0d3f10..57e97fd 100644
--- a/src/ssl_sock.c
+++ b/src/ssl_sock.c
@@ -3858,7 +3858,7 @@
 
 	/* at least one of the instances is using filters during the config
 	 * parsing, that's ok to inherit this during loading on CLI */
-	ckchs->filters = !!fcount;
+	ckchs->filters |= !!fcount;
 
 	/* Process each ckch and update keytypes for each CN/SAN
 	 * for example, if CN/SAN www.a.com is associated with
@@ -4102,7 +4102,7 @@
 
 	/* at least one of the instances is using filters during the config
 	 * parsing, that's ok to inherit this during loading on CLI */
-	ckchs->filters = !!fcount;
+	ckchs->filters |= !!fcount;
 
 	ctx = SSL_CTX_new(SSLv23_server_method());
 	if (!ctx) {