Added posix testsuite option.
diff --git a/testcases/Makefile b/testcases/Makefile
index f552ca0..d2b614e 100644
--- a/testcases/Makefile
+++ b/testcases/Makefile
@@ -3,6 +3,9 @@
 all:
 	@set -e; for i in $(SUBDIRS); do $(MAKE) -C $$i ; done
 
+posix:
+	@set -e; $(MAKE) -C open_posix_testsuite
+
 install:
 	mkdir -p bin
 	@set -e; for i in $(SUBDIRS); do $(MAKE) -C $$i install ; done