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/main.cpp b/logd/main.cpp
index c3343d7..5878f15 100644
--- a/logd/main.cpp
+++ b/logd/main.cpp
@@ -451,9 +451,8 @@
         pthread_attr_destroy(&attr);
     }
 
-    bool auditd = __android_logger_property_get_bool("logd.auditd",
-                                                     BOOL_DEFAULT_TRUE |
-                                                     BOOL_DEFAULT_FLAG_PERSIST);
+    bool auditd = __android_logger_property_get_bool("ro.logd.auditd",
+                                                     BOOL_DEFAULT_TRUE);
     if (drop_privs(klogd, auditd) != 0) {
         return -1;
     }
@@ -513,8 +512,8 @@
     if (auditd) {
         al = new LogAudit(logBuf, reader,
                           __android_logger_property_get_bool(
-                              "logd.auditd.dmesg",
-                              BOOL_DEFAULT_TRUE | BOOL_DEFAULT_FLAG_PERSIST)
+                              "ro.logd.auditd.dmesg",
+                              BOOL_DEFAULT_TRUE)
                                   ? fdDmesg
                                   : -1);
     }