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/libsysutils/src/ServiceManager.cpp b/libsysutils/src/ServiceManager.cpp
index 1abe988..13bac09 100644
--- a/libsysutils/src/ServiceManager.cpp
+++ b/libsysutils/src/ServiceManager.cpp
@@ -17,10 +17,12 @@
 #define LOG_TAG "Service"
 
 #include <errno.h>
+#include <stdio.h>
 #include <string.h>
+#include <unistd.h>
 
-#include <android/log.h>
 #include <cutils/properties.h>
+#include <log/log.h>
 #include <sysutils/ServiceManager.h>
 
 ServiceManager::ServiceManager() {