test-advise: check argument count with argc instead of argv

test-advise: check argument count with argc instead of argv

We complain if "test-tool advise" is not given an argument, but we
quietly ignore any additional arguments it receives. Let's instead check
that we got the expected number. As a bonus, this silences
-Wunused-parameter, which notes that we don't ever look at argc.

While we're here, we can also fix the indentation in the conditional.

Signed-off-by: Jeff King <redacted>
Signed-off-by: Junio C Hamano <redacted>