fix(library/constructions/projection): fix macro expansion
fix(library/constructions/projection): fix macro expansion

Thanks to @fpvandoorn for noticing this issue in Lean 2!  We encountered
this situation when the inferred type of the projection argument did not
reduce to the structure type with the current transparency setting of
the type context.

fpvandoorn/lean,leanprover-community/lean,dselsam/lean,Kha/lean,Kha/lean,avigad/lean,leodemoura/lean,dselsam/lean,johoelzl/lean,leodemoura/lean,digama0/lean,avigad/lean,digama0/lean,leanprover-community/lean,leodemoura/lean,leanprover-community/lean,dselsam/lean,leanprover/lean,avigad/lean,leanprover/lean,leanprover/lean,leanprover-community/lean,leanprover/lean,leanprover-community/lean,leodemoura/lean,Kha/lean,leodemoura/lean,dselsam/lean,fpvandoorn/lean,fpvandoorn/lean,leanprover/lean,avigad/lean,johoelzl/lean,leodemoura/lean,johoelzl/lean,fpvandoorn/lean,digama0/lean,Kha/lean,Kha/lean,leanprover-community/lean,Kha/lean,digama0/lean,digama0/lean,avigad/lean,leanprover/lean,johoelzl/lean,digama0/lean,avigad/lean,johoelzl/lean,fpvandoorn/lean,dselsam/lean,fpvandoorn/lean,dselsam/lean,johoelzl/lean