Reduces headers needed for external includes

hei_main.hpp included hei_isolator.hpp, which requires nearly all
headers in this project to be exported when building a library.

Change-Id: I6013ab53a7ee2b4993526bc4c62b30e8bf5f6702
Signed-off-by: Zane Shelley <zshelle@us.ibm.com>
diff --git a/test/simulator/simulator.hpp b/test/simulator/simulator.hpp
index 7d25160..ccb998a 100644
--- a/test/simulator/simulator.hpp
+++ b/test/simulator/simulator.hpp
@@ -2,6 +2,10 @@
 
 #include <hei_main.hpp>
 
+#include <algorithm>
+#include <map>
+#include <vector>
+
 #include "gtest/gtest.h"
 
 namespace libhei