otafault: Move to soong.

Test: mmma bootable/recovery
Change-Id: I5f2520ea457ba66743aa3aa1d5b3b488a93084a3
diff --git a/Android.bp b/Android.bp
index 49438ad..99ca3a4 100644
--- a/Android.bp
+++ b/Android.bp
@@ -1,4 +1,5 @@
 subdirs = [
     "bootloader_message",
+    "otafault",
     "otautil",
 ]