Commit integrate Make rules under test.

Signed-off-by: Garrett Cooper <yanegomi@gmail.com>
diff --git a/testcases/Makefile b/testcases/Makefile
index a0abbe8..ec9834a 100644
--- a/testcases/Makefile
+++ b/testcases/Makefile
@@ -40,4 +40,16 @@
 FILTER_OUT_DIRS		+= audit-test DOTS realtime
 endif
 
+open_posix_testsuite:
+	mkdir -p $@
+
+trunk-all: open_posix_testsuite-all
+
+trunk-clean:: open_posix_testsuite-clean
+
+trunk-install: open_posix_testsuite-install
+
+open_posix_testsuite-%: open_posix_testsuite
+	$(MAKE) -C $^ top_srcdir=$(top_srcdir)/testcases/$^ $*
+
 include $(top_srcdir)/include/mk/generic_trunk_target.mk