spurious output with BuiltinRule

Summary

Compiling with -fplugin=Foo -fno-omit-interface-pragmas causes GHC to output toHsRule: builtin <ru_name> if Foo adds a BuiltinRule.

The output comes from https://gitlab.haskell.org/ghc/ghc/-/blob/master/compiler/GHC/Iface/Make.hs#L696

Steps to reproduce

Hopefully the summary suffices.

Expected behavior

Not to output toHsRule: builtin .... If the message indicates a potential issue with generating interface pragmas with BuiltinRules, then the message should at least be more descriptive.

Environment

GHC version used: 8.8.3 (this still persists in master, though)

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