logd: Add support for ro.logd.auditd.[main|events]

log selinux audit messages boolean (true or false, default true)
selection for logging destinations:

ro.logd.auditd - turn on logd.auditd to pick up violations.
ro.logd.auditd.dmesg - to the kernel log.
ro.logd.auditd.main - to the "main" log buffer.
ro.logd.auditd.events - to the "events" log buffer.

We used to also read logd.auditd.dmesg and persist.logd.auditd.dmesg
which do not get refreshed when /data mounts internally.  This is a
confusing state as these properties will be read after a logd crash
and restart, adjusting the behavior of the logger.  Same can be said
for logd.auditd as well.  Drop reading these other parameters.

Test: manual set r/o parameters, stop/start logd to confirm behavior
Bug: 33969000
Bug: 27878170
Change-Id: I1a6bb4a903074c9aa7b227cf583a0094d49cbefd
diff --git a/logd/LogAudit.h b/logd/LogAudit.h
index ab30e28..844951d 100644
--- a/logd/LogAudit.h
+++ b/logd/LogAudit.h
@@ -26,7 +26,9 @@
 class LogAudit : public SocketListener {
     LogBuffer *logbuf;
     LogReader *reader;
-    int fdDmesg;
+    int fdDmesg; // fdDmesg >= 0 is functionally bool dmesg
+    bool main;
+    bool events;
     bool initialized;
 
 public: