message: allow obj-path and sig in STL containers

Allow object_path and signatures to be used in std::vector,
std::map, and std::unordered_map.

Change-Id: Ieb592aa518bfae08da393632a1dd0ed0dd684c7a
Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
diff --git a/test/message/native_types.cpp b/test/message/native_types.cpp
index 1ee3dee..df1cb96 100644
--- a/test/message/native_types.cpp
+++ b/test/message/native_types.cpp
@@ -1,5 +1,8 @@
 #include <cassert>
 #include <sdbusplus/message.hpp>
+#include <vector>
+#include <map>
+#include <unordered_map>
 
 int main()
 {
@@ -9,5 +12,14 @@
     std::string s2 = sdbusplus::message::signature("iii");
     sdbusplus::message::signature sig = s2;
 
+    std::vector<sdbusplus::message::signature> v =
+        { sdbusplus::message::signature("iii") };
+
+    std::map<sdbusplus::message::signature, int> m =
+        { { sdbusplus::message::signature("iii"), 1 } };
+
+    std::unordered_map<sdbusplus::message::signature, int> u =
+        { { sdbusplus::message::signature("iii"), 1 } };
+
     return 0;
 }