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/debuggerd/tombstone.cpp b/debuggerd/tombstone.cpp
index e2461c0..459e4cc 100644
--- a/debuggerd/tombstone.cpp
+++ b/debuggerd/tombstone.cpp
@@ -36,6 +36,7 @@
 #include <backtrace/Backtrace.h>
 #include <backtrace/BacktraceMap.h>
 #include <cutils/properties.h>
+#include <log/log.h>
 #include <log/logprint.h>
 #include <private/android_filesystem_config.h>
 #include <private/android_logger.h>