libc: Make calls to new user-space logger

* libc (fatal) logging now makes socket connection to the
  user-space logging service.
* Add a TARGET_USES_LOGD make flag for BoardConfig.mk to manage
  whether logd is enabled for use or not.

Change-Id: I96ab598c76d6eec86f9d0bc81094c1fb3fb0d9b4

libc/private/libc_logging.h

@@ -52,6 +52,17 @@ enum {
   ANDROID_LOG_SILENT,     /* only for SetMinPriority(); must be last */
 };
 
+enum {
+    LOG_ID_MIN = 0,
+
+    LOG_ID_MAIN = 0,
+    LOG_ID_RADIO = 1,
+    LOG_ID_EVENTS = 2,
+    LOG_ID_SYSTEM = 3,
+
+    LOG_ID_MAX
+};
+
 struct abort_msg_t {
   size_t size;
   char msg[0];