add -since flag to droiddoc options for 7.xml,
to apply api filtering to the reference
diff --git a/Android.mk b/Android.mk
index 6b75bcd..fb1a3a6 100644
--- a/Android.mk
+++ b/Android.mk
@@ -347,6 +347,7 @@
     -since ./frameworks/base/api/4.xml 4 \
     -since ./frameworks/base/api/5.xml 5 \
     -since ./frameworks/base/api/6.xml 6 \
+    -since ./frameworks/base/api/7.xml 7 \
 		-error 1 -error 2 -warning 3 -error 4 -error 6 -error 8 \
 		-overview $(LOCAL_PATH)/core/java/overview.html