CURRENT, CLANG 6: apache24, uid 80: exited on signal 11

Last weekend I updated a CURRENT server to recent CURRENT, > r328400 and performed
updates of the ports tree. Since Sunday, I receive segmenatation faults (SIG 11) when
accessing the server, especially with setup of nextcloud, refdb, phpldapadmin and any
other access with LDAP backend (all https).

The message on console is:

pid 23108 (httpd), uid 80: exited on signal 11
pid 32283 (httpd), uid 80: exited on signal 11
pid 21286 (httpd), uid 80: exited on signal 11
pid 10292 (httpd), uid 80: exited on signal 11

I do not see anything else! Neither in the log (no matter what log level I switch on) nor
elsewhere.

Configuration hasn't changed.

What the ... is up with the system? How can I dig into the problem?

Thanks for advices in advance,

Oliver
-- 
O. Hartmann

Ich widerspreche der Nutzung oder Übermittlung meiner Daten für
Werbezwecke oder für die Markt- oder Meinungsforschung (§ 28 Abs. 4 BDSG).