logd: missing klogd content

- regression in log_strtok_r (part deux) In commit
      'logd: fix kernel logline stutter'
  2c3b300fd8307e8da13608197d0a89bc613de5fb we introduced log_strtok_r.
  as a replacement for strtok_r that dealt with a problem with
  some kernel log messages. Fix is to refine definition of
  is_timestamp to not match on patterns like [0], requiring
  a single period. Another fix is to refine definition of
  is_prio to properly escape non-digit content.
- Missing content because SYSLOG_ACTION_SIZE_BUFFER with added logging
  is too short for full read of SYSLOG_ACTION_READ_ALL dropping
  initial content. Add a margin for additional 1024 bytes.
- Absolute _first_ log entry has sequence number of 1, which is
  specifically dropped, start sequence count at 1 rather than 0.
- Remove trailing space for efficiency.
- If tag exists but no content, trick into kernel logging.

Bug: 21851884
Change-Id: I0867a555a3bca09bbf18d18e75e41dffffe57a23
diff --git a/logd/LogBufferElement.cpp b/logd/LogBufferElement.cpp
index 7df1123..3f5fdce 100644
--- a/logd/LogBufferElement.cpp
+++ b/logd/LogBufferElement.cpp
@@ -30,7 +30,7 @@
 #include "LogReader.h"
 
 const uint64_t LogBufferElement::FLUSH_ERROR(0);
-atomic_int_fast64_t LogBufferElement::sequence;
+atomic_int_fast64_t LogBufferElement::sequence(1);
 
 LogBufferElement::LogBufferElement(log_id_t log_id, log_time realtime,
                                    uid_t uid, pid_t pid, pid_t tid,