Add unittest for payload_generation_config_android.

Bug: 28171891
Test: update_engine_unittests
Change-Id: Id2566cfe4167da90fbb00e0e29700841db206edc
diff --git a/Android.mk b/Android.mk
index eb31771..19ef765 100644
--- a/Android.mk
+++ b/Android.mk
@@ -969,6 +969,7 @@
     payload_generator/inplace_generator_unittest.cc \
     payload_generator/mapfile_filesystem_unittest.cc \
     payload_generator/payload_file_unittest.cc \
+    payload_generator/payload_generation_config_android_unittest.cc \
     payload_generator/payload_generation_config_unittest.cc \
     payload_generator/payload_signer_unittest.cc \
     payload_generator/squashfs_filesystem_unittest.cc \