liblog: only allow one transport for reading

liblog has left over code from local_logger that allows for reading
from multiple sources and merging the contents.  Since we've already
removed local_logger, this change removes the rest of this code.

Test: liblog-unit-tests
Change-Id: I5685ad6c1e7cbcaa0a660ed10f47714784a40791
diff --git a/liblog/logger.h b/liblog/logger.h
index accb6e7..4b4ef5f 100644
--- a/liblog/logger.h
+++ b/liblog/logger.h
@@ -95,9 +95,19 @@
                       size_t len);
 };
 
+struct android_log_transport_context {
+  union android_log_context_union context; /* zero init per-transport context */
+
+  struct android_log_transport_read* transport;
+  unsigned logMask;      /* mask of requested log buffers */
+  int ret;               /* return value associated with following data */
+  struct log_msg logMsg; /* peek at upcoming data, valid if logMsg.len != 0 */
+};
+
 struct android_log_logger_list {
   struct listnode logger;
-  struct listnode transport;
+  android_log_transport_context transport_context;
+  bool transport_initialized;
   int mode;
   unsigned int tail;
   log_time start;
@@ -111,27 +121,7 @@
   log_id_t logId;
 };
 
-struct android_log_transport_context {
-  struct listnode node;
-  union android_log_context_union context; /* zero init per-transport context */
-  struct android_log_logger_list* parent;
-
-  struct android_log_transport_read* transport;
-  unsigned logMask;      /* mask of requested log buffers */
-  int ret;               /* return value associated with following data */
-  struct log_msg logMsg; /* peek at upcoming data, valid if logMsg.len != 0 */
-};
-
 /* assumes caller has structures read-locked, single threaded, or fenced */
-#define transport_context_for_each(transp, logger_list)                          \
-  for ((transp) = node_to_item((logger_list)->transport.next,                    \
-                               struct android_log_transport_context, node);      \
-       ((transp) != node_to_item(&(logger_list)->transport,                      \
-                                 struct android_log_transport_context, node)) && \
-       ((transp)->parent == (logger_list));                                      \
-       (transp) = node_to_item((transp)->node.next,                              \
-                               struct android_log_transport_context, node))
-
 #define logger_for_each(logp, logger_list)                          \
   for ((logp) = node_to_item((logger_list)->logger.next,            \
                              struct android_log_logger, node);      \