[ectoplasm]

Yes, of course, it's just the first step. In fact you'd probably need to introduce a couple more variables. For example, i gets defined three times:

  i = sk_X509_num(ctx->chain);
  i = check_trust(ctx);
  i = X509_chain_check_suiteb(&ctx->error_depth, NULL, ctx->chain, ctx->param->flags);

What a mess. I would probably start by moving towards a module / class for all the functions that take either an X509_STORE_CTX *ctx pointer or something accessed through ctx.