diag-mode: return InTest if host is in diag mode

Per discussion with DMTF and clarification of InTest state within
http://redfish.dmtf.org/schemas/v1/Resource.json#/definitions/Status
it was determined that this would represent the situation where the host
is collecting diagnostic data. This maps to the new DiagnosticMode
state added to the xyz.openbmc_project.State.Host.HostState namespace.

Tested:
Verified that Redfish API returned expected result when in
DiagnosticMode:
  "Status": {
    "Health": "OK",
    "HealthRollup": "OK",
    "State": "InTest"
  },

Change-Id: I1c5deb5fdc251a5dcd4d1d01f4eedb6c507ded0a
Signed-off-by: Andrew Geissler <geissonator@yahoo.com>
diff --git a/redfish-core/lib/systems.hpp b/redfish-core/lib/systems.hpp
index 2e88367..cae0fe8 100644
--- a/redfish-core/lib/systems.hpp
+++ b/redfish-core/lib/systems.hpp
@@ -617,6 +617,12 @@
                     aResp->res.jsonValue["PowerState"] = "On";
                     aResp->res.jsonValue["Status"]["State"] = "Enabled";
                 }
+                else if (*s == "xyz.openbmc_project.State.Host.HostState."
+                               "DiagnosticMode")
+                {
+                    aResp->res.jsonValue["PowerState"] = "On";
+                    aResp->res.jsonValue["Status"]["State"] = "InTest";
+                }
                 else
                 {
                     aResp->res.jsonValue["PowerState"] = "Off";