Add annotations about potential problem regions to validation VCFs.

def _annotate_validations(eval_files, data):
    """Add annotations about potential problem regions to validation VCFs.
    """
    for key in ["tp", "tp-calls", "fp", "fn"]:
        if eval_files.get(key):
            eval_files[key] = annotation.add_genome_context(eval_files[key], data)
    return eval_files