[mod_authn_ldap] ldap_set_option LDAP_OPT_RESTART (fixes #2940)

ldap_set_option LDAP_OPT_RESTART to handle EINTR on SIGCHLD from CGI

(ldap uses poll(), which is not restartable with sigaction SA_RESTART)

x-ref:
  "mod_authn_ldap/mod_cgi race condition, "Can't contact LDAP server""
  https://redmine.lighttpd.net/issues/2940

src/mod_authn_ldap.c

@@ -404,6 +404,9 @@ static LDAP * mod_authn_ldap_host_init(server *srv, plugin_config *s) {
         return NULL;
     }
 
+    /* restart ldap functions if interrupted by a signal, e.g. SIGCHLD */
+    ldap_set_option(ld, LDAP_OPT_RESTART, LDAP_OPT_ON);
+
     if (s->auth_ldap_starttls) {
         /* if no CA file is given, it is ok, as we will use encryption
          * if the server requires a CAfile it will tell us */

src/mod_vhostdb_ldap.c

@@ -256,6 +256,9 @@ static LDAP * mod_authn_ldap_host_init(server *srv, vhostdb_config *s) {
         return NULL;
     }
 
+    /* restart ldap functions if interrupted by a signal, e.g. SIGCHLD */
+    ldap_set_option(ld, LDAP_OPT_RESTART, LDAP_OPT_ON);
+
     if (s->starttls) {
         /* if no CA file is given, it is ok, as we will use encryption
          * if the server requires a CAfile it will tell us */