Add conflict markers for dba tests

These tests use the same filename, and as such must not be run in
parallel.

Author: cmb69

ext/dba/tests/dba_optimize.phpt

@@ -2,6 +2,8 @@
 DBA Optimize Test
 --EXTENSIONS--
 dba
+--CONFLICTS--
+dba
 --SKIPIF--
 <?php
     require_once __DIR__ .'/skipif.inc';

ext/dba/tests/gh9155.phpt

@@ -2,6 +2,8 @@
 Bug GH-9155 (dba_open("non-existing", "c-", "flatfile") segfaults)
 --EXTENSIONS--
 dba
+--CONFLICTS--
+dba
 --SKIPIF--
 <?php
 $handler = "flatfile";

ext/dba/tests/value_errors_open.phpt

@@ -2,6 +2,8 @@
 DBA argument tests
 --EXTENSIONS--
 dba
+--CONFLICTS--
+dba
 --SKIPIF--
 <?php
 require_once(__DIR__ .'/skipif.inc');