Re-enable disable_sparse properties.

This accidentally got omitted in the recent refactoring of
generate-image-prop-dictionary.

Bug: N/A
Test: build, system.img is not sparsed
Change-Id: Ie2e095aff08e937111f5c7ffc06e38e87c2d7d43
diff --git a/core/Makefile b/core/Makefile
index 352ab1a..54ce1bd 100644
--- a/core/Makefile
+++ b/core/Makefile
@@ -1634,6 +1634,8 @@
 $(eval _size := $(BOARD_$(_var)IMAGE_PARTITION_SIZE))
 $(eval _reserved := $(BOARD_$(_var)IMAGE_PARTITION_RESERVED_SIZE))
 $(eval _headroom := $(PRODUCT_$(_var)_HEADROOM))
+$(if $(or $(_size), $(_reserved), $(_headroom)),,
+    $(hide) echo "$(1)_disable_sparse=true" >> $(2))
 $(call add-common-flags-to-image-props,$(1),$(2))
 endef