New product config flag to gate blueprint modules

Example usage:
PRODUCT_INCLUDE_TAGS += use_myspecial_sdk

This also populates the allowlist with go/nogo mainline tags. Usage of
`PRODUCT_INCLUDE_TAGS` outside this allowlist will raise an error
in product config

Test: TH

Change-Id: Ica82a8f65cbfda600d72fc54fb873c1eaa1666a7
diff --git a/core/product.mk b/core/product.mk
index 4c642b8..7621c71 100644
--- a/core/product.mk
+++ b/core/product.mk
@@ -263,6 +263,9 @@
 # This flag implies PRODUCT_USE_DYNAMIC_PARTITIONS.
 _product_single_value_vars += PRODUCT_RETROFIT_DYNAMIC_PARTITIONS
 
+# List of tags that will be used to gate blueprint modules from the build graph
+_product_list_vars += PRODUCT_INCLUDE_TAGS
+
 # When this is true, various build time as well as runtime debugfs restrictions are enabled.
 _product_single_value_vars += PRODUCT_SET_DEBUGFS_RESTRICTIONS