Enable incidentd access to ro.boot.bootreason

incident report contains similar data as in a bugreport, but in proto
format.

Test: adb shell incident -p LOCAL 1000
Bug: 152173578
Change-Id: Iee53a3b8a6c95629a1d5c15b4d17f3d680b14178

private/bootstat.te

@@ -15,6 +15,7 @@ neverallow {
   -bootanim
   -bootstat
   -dumpstate
+  userdebug_or_eng(`-incidentd')
   -init
   -recovery
   -shell

private/incidentd.te

@@ -168,6 +168,14 @@ userdebug_or_eng(`
   get_prop(incidentd, serialno_prop)
 ')
 
+# Read ro.boot.bootreason, persist.sys.boot.bootreason
+# This is used to track reports from lab testing devices
+userdebug_or_eng(`
+  get_prop(incidentd, bootloader_boot_reason_prop);
+  get_prop(incidentd, system_boot_reason_prop);
+  get_prop(incidentd, last_boot_reason_prop);
+')
+
 ###
 ### neverallow rules
 ###