liblog: add pstore read

Used to pull the Android log messages after a reboot. Adding
an ANDROID_LOG_PSTORE flag to the mode parameter in calls to
android_logger_list_alloc() and android_logger_list_alloc_time().
The side effects are that android_logger_clear() and
android_logger_list_read() will react with the user space
pstore driver. Forms a companion to the pstore console logs.

Change-Id: I7bb07b87b3bf73f059a21af3f810af37c7715b6d
diff --git a/liblog/README b/liblog/README
index 0676aec..461dfbe 100644
--- a/liblog/README
+++ b/liblog/README
@@ -116,6 +116,10 @@
        code,  otherwise the  android_logger_list_read  call will block for new
        entries.
 
+       The  ANDROID_LOG_PSTORE mode flag to the android_logger_open is used to
+       switch from the active logs to the persistent logs from before the last
+       reboot.
+
        The value returned by android_logger_open can be used as a parameter to
        the  android_logger_clear  function to empty the sub-log.  It is recom‐
        mended to only open log ANDROID_LOG_WRONLY in that case.
@@ -132,4 +136,4 @@
 
 
 
-                                  17 Dec 2013                        LIBLOG(3)
+                                  24 Jan 2014                        LIBLOG(3)