MINOR: logs: Use dedicated function to init/deinit log buffers

Now, we use init_log_buffers and deinit_log_buffers to, respectively, initialize
and deinitialize log buffers used for syslog messages.

These functions have been introduced to be used by threads, to deal with
thread-local log buffers.
diff --git a/include/proto/log.h b/include/proto/log.h
index 2d4ca84..72ff744 100644
--- a/include/proto/log.h
+++ b/include/proto/log.h
@@ -53,6 +53,11 @@
  */
 void init_log();
 
+
+/* Initialize/Deinitialize log buffers used for syslog messages */
+int init_log_buffers();
+void deinit_log_buffers();
+
 /*
  * Builds a log line.
  */