Add flag to disable rild compilation

This change adds a flag to disable rild
compilation. Vendors implementing their
own version should enable this flag in their
device specific make files.

Bug: 71513817
Test: Compile and check the out folder for rild
Change-Id: Ifce51b803adb97e03c9d27b9415dc3fa5714e71e
diff --git a/rild/Android.mk b/rild/Android.mk
index 7ac505c..57a9d48 100644
--- a/rild/Android.mk
+++ b/rild/Android.mk
@@ -1,5 +1,7 @@
 # Copyright 2006 The Android Open Source Project
 
+ifndef ENABLE_VENDOR_RIL_SERVICE
+
 LOCAL_PATH:= $(call my-dir)
 include $(CLEAR_VARS)
 
@@ -31,3 +33,4 @@
 
 include $(BUILD_EXECUTABLE)
 
+endif