kmsrecorderendpoint: Protect sync variables from concurrent access
kmsrecorderendpoint: Protect sync variables from concurrent access

Change-Id: I8d1c542b93baeaaa0161c84f39c9f4198dddc7e1

TribeMedia/kms-core,TribeMedia/kms-core,Kurento/kms-core,Kurento/kms-core,ESTOS/kms-core,Kurento/kms-core,shelsonjava/kms-core,shelsonjava/kms-core,shelsonjava/kms-core,ESTOS/kms-core,KurentoLegacy/gst-kurento-plugins,Kurento/kms-core,shelsonjava/kms-core,KurentoLegacy/gst-kurento-plugins,TribeMedia/kms-core,ESTOS/kms-core,KurentoLegacy/gst-kurento-plugins,ESTOS/kms-core,KurentoLegacy/gst-kurento-plugins,TribeMedia/kms-core