systems: fix Members@odata.count is incorrect even Members have contents

Issue symptom:
Run automation test "Verify_Systems_Defaults" then we got ERROR as below.
Verify Systems Defaults :: Verify systems defaults.                   | FAIL |
**ERROR** Invalid variable value: systems['Members@odata.count']:     0 <int>

Root cause:
In Systems, doGet() didn't calculate count after ifaceArray.push_back({{"@odata.id", "/redfish/v1/Systems/system"}})

Solution:
Increase count by ifaceArray.size() after ifaceArray.push_back() in Systems

Tested:
1. Verified
   robot -t Verify_Systems_Defaults redfish/service_root/test_sessions_management.robot
   Verify Systems Defaults :: Verify systems defaults.                | PASS |

2. Verified system detail from Redfish.
   Get https://<BMC-IP>/redfish/v1/Systems
   Response:
   {
      "@odata.id": "/redfish/v1/Systems",
      "@odata.type": "#ComputerSystemCollection.ComputerSystemCollection",
      "Members": [
         {
            "@odata.id": "/redfish/v1/Systems/system"
         }
      ],
      "Members@odata.count": 1,
      "Name": "Computer System Collection"
   }

Signed-off-by: Tim Lee <timlee660101@gmail.com>
Change-Id: I9cdb5dac9e16851112085048bc674808511a4845

1 files changed, 1 insertions, 1 deletions

diff --git a/redfish-core/lib/systems.hpp b/redfish-core/lib/systems.hpp
index ef178ed203..89a8ad5b1d 100644
--- a/redfish-core/lib/systems.hpp
+++ b/redfish-core/lib/systems.hpp
@@ -1769,9 +1769,9 @@ class SystemsCollection : public Node
                     asyncResp->res.jsonValue["Members"];
                 ifaceArray = nlohmann::json::array();
                 auto& count = asyncResp->res.jsonValue["Members@odata.count"];
-                count = 0;
                 ifaceArray.push_back(
                     {{"@odata.id", "/redfish/v1/Systems/system"}});
+                count = ifaceArray.size();
                 if (!ec)
                 {
                     BMCWEB_LOG_DEBUG << "Hypervisor is available";