Disable test unit.pcre_test on s390x that was failing in stretch-security

Upstream developer confirmed the test is unimportant and it is OK to allow it to fail. https://jira.mariadb.org/browse/MDEV-17865

Disable test unit.pcre_test on s390x that was failing in stretch-security
Upstream developer confirmed the test is unimportant and it is OK to allow it to fail. https://jira.mariadb.org/browse/MDEV-17865
ecba2e88 · Otto Kekäläinen · 33d85312 · ecba2e88
Commit ecba2e88 authored Nov 29, 2018 by Otto Kekäläinen
--- a/debian/unstable-tests.s390x
+++ b/debian/unstable-tests.s390x
+unit.pcre_test : MDEV-17865