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/libcutils/Android.bp b/libcutils/Android.bp
index f7b497d..39f8aba 100644
--- a/libcutils/Android.bp
+++ b/libcutils/Android.bp
@@ -18,6 +18,7 @@
 // they correspond to features not used by our host development tools
 // which are also hard or even impossible to port to native Win32
 libcutils_nonwindows_sources = [
+    "android_get_control_file.cpp",
     "fs.c",
     "multiuser.c",
     "socket_inaddr_any_server_unix.c",
@@ -34,7 +35,6 @@
     host_supported: true,
     srcs: [
         "config_utils.c",
-        "files.cpp",
         "fs_config.c",
         "canned_fs_config.c",
         "hashmap.c",