add db_field_log::mask

Allow filters to distingush DBE_PROPERTY

modules/database/src/ioc/db/dbEvent.c

@@ -714,6 +714,7 @@ db_field_log* db_create_event_log (struct evSubscrip *pevent)
 {
     db_field_log *pLog = db_create_field_log(pevent->chan, pevent->useValque);
     if (pLog) {
+        pLog->mask = pevent->select;
         pLog->ctx  = dbfl_context_event;
     }
     return pLog;

modules/database/src/ioc/db/db_field_log.h

@@ -109,6 +109,8 @@ typedef struct db_field_log {
     unsigned int     type:1;  /* type (union) selector */
     /* ctx is used for all types */
     unsigned int      ctx:1;  /* context (operation type) */
+    /* only for dbfl_context_event */
+    unsigned char      mask;  /* DBE_* mask */
     /* the following are used for value and reference types */
     epicsTimeStamp     time;  /* Time stamp */
     unsigned short     stat;  /* Alarm Status */