Make code compile on clang again

There are a couple places we missed inline/static on our headers, and a
couple unused message entry callbacks for which their parameters were
incorrect (which clang caught).  Fix all of them.

Tested: Code compiles on clang.  No-op changes.

Signed-off-by: Ed Tanous <edtanous@google.com>
Change-Id: I12c9c04d3b773c4991c6cd92d0cfd42b348762d6
diff --git a/redfish-core/lib/log_services.hpp b/redfish-core/lib/log_services.hpp
index 8a0bd3a..4b48873 100644
--- a/redfish-core/lib/log_services.hpp
+++ b/redfish-core/lib/log_services.hpp
@@ -2842,7 +2842,8 @@
     invalid,
 };
 
-OEMDiagnosticType getOEMDiagnosticType(const std::string_view& oemDiagStr)
+inline OEMDiagnosticType
+    getOEMDiagnosticType(const std::string_view& oemDiagStr)
 {
     if (oemDiagStr == "OnDemand")
     {