Enable cppcoreguidelines check on the repo

This commit adds cppcoreguidelines clang-tidy
checks and make necessary changes.

Change-Id: I402b82f96b7ff82e3ba6d84c9cc50435c1ead6d4
Signed-off-by: Pavithra Barithaya <pavithra.b@ibm.com>
diff --git a/bmc_epoch.cpp b/bmc_epoch.cpp
index ad65777..05068ce 100644
--- a/bmc_epoch.cpp
+++ b/bmc_epoch.cpp
@@ -65,7 +65,7 @@
         elog<InternalFailure>();
     }
 
-    sd_event_source* es;
+    sd_event_source* es = nullptr;
     r = sd_event_add_io(bus.get_event(), &es, timeFd, EPOLLIN, onTimeChange,
                         this);
     if (r < 0)