Add _PID information in elog  AdditionalData

dreport need PID information to collect process specific journal
for InternalFailure type error triggered dump.

Change-Id: I313caa4795f7c0d47c1f42dae0653008cdbd5967
Signed-off-by: Jayanth Othayoth <ojayanth@in.ibm.com>
diff --git a/log_manager.cpp b/log_manager.cpp
index 29c0ffe..b535039 100644
--- a/log_manager.cpp
+++ b/log_manager.cpp
@@ -71,6 +71,9 @@
         metalist.insert(metamap->second.begin(), metamap->second.end());
     }
 
+    //Add _PID field information in AdditionalData.
+    metalist.insert("_PID");
+
     std::vector<std::string> additionalData;
 
     // Read the journal from the end to get the most recent entry first.