Pass --legacy to aapt2 compile for Dialer

This module produces warnings that are treated as errors if --legacy
is not passed.  --legacy is no longer being passed by default, so
add it here.

Bug: 135615364
Test: m java
Change-Id: I4db9606206597a58b2a6864ac5ef6d944bb292b4
diff --git a/Android.mk b/Android.mk
index b7a4a8f..e50b0a5 100644
--- a/Android.mk
+++ b/Android.mk
@@ -97,6 +97,7 @@
 LOCAL_AAPT_FLAGS += \
 	--auto-add-overlay \
 	--extra-packages me.leolin.shortcutbadger \
+	--legacy \
 
 LOCAL_STATIC_JAVA_LIBRARIES := \
 	android-common \