Fix rules for general_property_contexts.

Failed to include base_rules.mk, so this target was not being built.

Change-Id: I2414fa6c3e3e37c74f63c205e3694d1a811c956e
Signed-off-by: Stephen Smalley <sds@tycho.nsa.gov>
diff --git a/Android.mk b/Android.mk
index f9c96ad..af7476e 100644
--- a/Android.mk
+++ b/Android.mk
@@ -267,6 +267,8 @@
 LOCAL_MODULE_CLASS := ETC
 LOCAL_MODULE_TAGS := tests
 
+include $(BUILD_SYSTEM)/base_rules.mk
+
 $(LOCAL_BUILT_MODULE): PRIVATE_SEPOLICY := $(built_sepolicy)
 $(LOCAL_BUILT_MODULE) : $(addprefix $(LOCAL_PATH)/, property_contexts) $(built_sepolicy) $(HOST_OUT_EXECUTABLES)/checkfc
 	@mkdir -p $(dir $@)