php: Enable testcase director_stl

This already had a _runme.php which passes as-is, but wasn't listed to
be run.
diff --git a/Examples/test-suite/php/Makefile.in b/Examples/test-suite/php/Makefile.in
index 693615b..741395a 100644
--- a/Examples/test-suite/php/Makefile.in
+++ b/Examples/test-suite/php/Makefile.in
@@ -11,6 +11,7 @@
 
 CPP_TEST_CASES += \
 	callback \
+	director_stl \
 	li_factory \
 	php_iterator \
 	php_namewarn_rename \