Support LOCAL_INIT_RC.

A module can install a companion init.rc file,
by specifying:
LOCAL_INIT_RC := <init.rc-file-path-replative-to-LOCAL_PATH>
You can also use the variant with _32 or _64 suffix.

Bug: 23186545
Change-Id: I00a96509f5707ae39361a0c5555fa59d46c90322
diff --git a/core/clear_vars.mk b/core/clear_vars.mk
index 431c688..c42a8e0 100644
--- a/core/clear_vars.mk
+++ b/core/clear_vars.mk
@@ -181,6 +181,7 @@
 LOCAL_SANITIZE:=
 LOCAL_SANITIZE_RECOVER:=
 LOCAL_DBUS_PROXY_PREFIX:=
+LOCAL_INIT_RC:=
 
 # arch specific variables
 LOCAL_SRC_FILES_$(TARGET_ARCH):=
@@ -288,6 +289,8 @@
 LOCAL_MODULE_STEM_64:=
 LOCAL_CLANG_32:=
 LOCAL_CLANG_64:=
+LOCAL_INIT_RC_32:=
+LOCAL_INIT_RC_64:=
 
 # Trim MAKEFILE_LIST so that $(call my-dir) doesn't need to
 # iterate over thousands of entries every time.