liblog: fix reading pmsg am: 709d569241

Original change: https://googleplex-android-review.googlesource.com/c/platform/system/core/+/11899686

Change-Id: I9f2448268928c18343a2e22964437c8edd3a2cad
diff --git a/liblog/pmsg_reader.cpp b/liblog/pmsg_reader.cpp
index d006ba4..3bdc30f 100644
--- a/liblog/pmsg_reader.cpp
+++ b/liblog/pmsg_reader.cpp
@@ -96,7 +96,7 @@
           ((logger_list->start.tv_sec != buf.l.realtime.tv_sec) ||
            (logger_list->start.tv_nsec <= buf.l.realtime.tv_nsec)))) &&
         (!logger_list->pid || (logger_list->pid == buf.p.pid))) {
-      char* msg = reinterpret_cast<char*>(&log_msg->entry) + log_msg->entry.hdr_size;
+      char* msg = reinterpret_cast<char*>(&log_msg->entry) + sizeof(log_msg->entry);
       *msg = buf.prio;
       fd = atomic_load(&logger_list->fd);
       if (fd <= 0) {