Allow to explicitly compile the core build configuration

Also add some missing copyright notices

Change-Id: I86873ad58f3dadbec8be741982bed548cb7e3c8e
diff --git a/target/product/AndroidProducts.mk b/target/product/AndroidProducts.mk
index c435177..94b0e24 100644
--- a/target/product/AndroidProducts.mk
+++ b/target/product/AndroidProducts.mk
@@ -26,6 +26,7 @@
 #
 
 PRODUCT_MAKEFILES := \
+    $(LOCAL_DIR)/core.mk \
     $(LOCAL_DIR)/generic.mk \
     $(LOCAL_DIR)/sdk.mk \
     $(LOCAL_DIR)/sim.mk