Cannot update firebird25 after recent icu update

[Walter Schwarzenfeld]

I am sure the thunderbird and firefox problems disappeared if I reverted 
the icu update and recompiled firefox, libxul and thunderbird.

https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=210878
https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=210879