init: remove last init.cpp global

By moving it into builtins.cpp..., but that's less bad than it is
now, especially since this is defunct in code targeting Q+.  Remove
the guards that init.h isn't being included by other files too as it's
not useful anymore.

Test: build
Change-Id: Ic564fcff9e8716ec924098b07a8c9d94ca25f960
diff --git a/init/init.cpp b/init/init.cpp
index 2b94825..b6911e5 100644
--- a/init/init.cpp
+++ b/init/init.cpp
@@ -28,9 +28,11 @@
 #include <sys/types.h>
 #include <unistd.h>
 
+#include <functional>
 #include <map>
 #include <memory>
 #include <optional>
+#include <vector>
 
 #include <android-base/chrono_utils.h>
 #include <android-base/file.h>
@@ -54,6 +56,7 @@
 
 #include "action_parser.h"
 #include "boringssl_self_test.h"
+#include "builtins.h"
 #include "epoll.h"
 #include "first_stage_init.h"
 #include "first_stage_mount.h"
@@ -100,8 +103,6 @@
 static bool do_shutdown = false;
 static bool load_debug_prop = false;
 
-std::vector<std::string> late_import_paths;
-
 static std::vector<Subcontext>* subcontexts;
 
 void DumpState() {