8213617: JFR should record the PID of the recorded process

Reviewed-by: mgronlun

src/share/vm/jfr/metadata/metadata.xml

@@ -607,7 +607,8 @@
     <Field type="string" name="jvmFlags" label="JVM Settings File Arguments" />
     <Field type="string" name="javaArguments" label="Java Application Arguments" />
     <Field type="long" contentType="epochmillis" name="jvmStartTime" label="JVM Start Time" />
-  </Event>
+    <Field type="long" name="pid" label="Process Identifier" />
+     </Event>
 
   <Event name="OSInformation" category="Operating System" label="OS Information" period="endChunk">
     <Field type="string" name="osVersion" label="OS Version" />

src/share/vm/jfr/periodic/jfrPeriodic.cpp

@@ -74,6 +74,7 @@ TRACE_REQUEST_FUNC(JVMInformation) {
   event.set_jvmArguments(Arguments::jvm_args());
   event.set_jvmFlags(Arguments::jvm_flags());
   event.set_jvmStartTime(Management::vm_init_done_time());
+  event.set_pid(os::current_process_id());
   event.commit();
  }