system/core: preparation to pull back interfaces from android/log.h

Point to log/log.h where necessary, define LOG_TAG where necessary.
Accept that private/android_logger.h is suitable replacement for
log/logger.h and android/log.h.

Correct liblog/README

Effectively a cleanup and controlled select revert of
'system/core: drop or replace log/logger.h' and
'system/core: Replace log/log.h with android/log.h'.

Test: compile
Bug: 30465923
Change-Id: Ic2ad157bad6f5efe2c6af293a73bb753300b17a2
diff --git a/libcutils/sockets_unix.cpp b/libcutils/sockets_unix.cpp
index e51a1c7..3545403 100644
--- a/libcutils/sockets_unix.cpp
+++ b/libcutils/sockets_unix.cpp
@@ -14,7 +14,11 @@
  * limitations under the License.
  */
 
+#define LOG_TAG "socket-unix"
+
 #include <sys/uio.h>
+#include <time.h>
+#include <unistd.h>
 
 #include <android/log.h>
 #include <cutils/sockets.h>