libcutils: move cutils/files.h to cutils/android_get_control_file.h

files.[h|cpp] is bound to be abused with junk, replace with
android_get_control_file.[h|cpp]. Plus some sundry cleanup.

Test: gTest libcutils-tests, logd-unit-tests, liblog-unit-tests,
      logcat-unit-tests and init_tests
Bug: 32450474
Change-Id: Ibd4a7aa4624ea19a43d1f98a3c71ac37805d36b5
diff --git a/init/descriptors.cpp b/init/descriptors.cpp
index 10aae88..429a76e 100644
--- a/init/descriptors.cpp
+++ b/init/descriptors.cpp
@@ -23,7 +23,7 @@
 #include <unistd.h>
 
 #include <android-base/stringprintf.h>
-#include <cutils/files.h>
+#include <cutils/android_get_control_file.h>
 #include <cutils/sockets.h>
 
 #include "init.h"