Fix a few coverity "Use after NULL check" warnings

Also remove the unit test mocks that allowed get_options() to be
NULL; that's an invariant violation for get_options().

src/or/cpuworker.c

@@ -359,8 +359,7 @@ cpuworker_onion_handshake_replyfn(void *work_)
     log_debug(LD_OR,
               "decoding onionskin failed. "
               "(Old key or bad software.) Closing.");
-    if (circ)
-      circuit_mark_for_close(TO_CIRCUIT(circ), END_CIRC_REASON_TORPROTOCOL);
+    circuit_mark_for_close(TO_CIRCUIT(circ), END_CIRC_REASON_TORPROTOCOL);
     goto done_processing;
   }