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
3 files changed