Enable init checker

clang-tidy added cppcoreguidelines-init-variables as a check, which is
something we already enforce to some extent, but getting CI to enforce
it will help reviews move faster.

Tested: Code compiles.  Noop changes.

Signed-off-by: Ed Tanous <edtanous@google.com>
Change-Id: I7e10950de617b1d3262265572b1703f2e60b69d0
diff --git a/redfish-core/lib/message_registries.hpp b/redfish-core/lib/message_registries.hpp
index ae02189..cfa2bf5 100644
--- a/redfish-core/lib/message_registries.hpp
+++ b/redfish-core/lib/message_registries.hpp
@@ -62,7 +62,7 @@
     const crow::Request&, const std::shared_ptr<bmcweb::AsyncResp>& asyncResp,
     const std::string& registry)
 {
-    const message_registries::Header* header;
+    const message_registries::Header* header = nullptr;
     std::string dmtf = "DMTF ";
     const char* url = nullptr;
 
@@ -127,7 +127,7 @@
     const std::string& registry, const std::string& registryMatch)
 
 {
-    const message_registries::Header* header;
+    const message_registries::Header* header = nullptr;
     std::vector<const message_registries::MessageEntry*> registryEntries;
     if (registry == "Base")
     {