Remove obsolete output_to_genfiles = True.

[tjgq]

This is a no-op for Bazel, which enables --incompatible_merge_genfiles_directory by default.

[fruffy]

Approving, but can you give some more detail on the rationale here? It can't hurt to make this explicit, even if it is the default value.

[tjgq]

Approving, but can you give some more detail on the rationale here? It can't hurt to make this explicit, even if it is the default value.

When --incompatible_merge_genfiles_directory is enabled (which is the case for Bazel, but not Blaze at Google), output_to_genfiles has no effect - it doesn't matter what you set it to. I'm making this change because we want to switch the default at Google, but we can't flip the flag globally - we have to do it rule by rule (and we import this rule for use internally).

Once we're done, output_to_genfiles will be removed entirely, so there's no advantage to leaving it here explicitly set to False. 99% of Bazel users don't encounter the genfiles directory at all, so leaving it is in fact more confusing.

[fruffy]

Thanks!