Use vendor/etc/ueventd.rc on microdroid

... because vendors should be able to extend ueventd.rc for their own
devices (in microdroid) and microdroid's system.img can't be amended.

Bug: N/A
Test: boot microdroid
Change-Id: I7ceaf3f87453c8e29f9d9bf03d4d1866185d4fec
diff --git a/init/ueventd.cpp b/init/ueventd.cpp
index 586e2cf..3f0d0e9 100644
--- a/init/ueventd.cpp
+++ b/init/ueventd.cpp
@@ -297,6 +297,10 @@
 }
 
 static UeventdConfiguration GetConfiguration() {
+    if (IsMicrodroid()) {
+        return ParseConfig({"/system/etc/ueventd.rc", "/vendor/etc/ueventd.rc"});
+    }
+
     auto hardware = android::base::GetProperty("ro.hardware", "");
 
     struct LegacyPathInfo {