...after 6a312a4a "Prepare external/firebird for
sanitizers".  Doing `make check screenshot` on Linux with Clang
-fsanitize=undefined -fsanitize=local-bounds -fsanitize=nullability works now.

Patches that might be unwanted in non-UBSan builds are added to sanitizer.patch
while unproblematic ones are added to always-included ubsan.patch.

CppunitTest_dbaccess_firebird_test, e.g., shows that
comphelper::AsyncEventNotifierAutoJoin::onTerminated called base-class
osl::Thread::onTerminated (which does nothing, anyway) of an already destroyed
object, so just drop that.

Change-Id: If50f442ee6dbe590db843c38681d1c1cade8fa6a
Reviewed-on: https://gerrit.libreoffice.org/47122Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Stephan Bergmann <sbergman@redhat.com>