Check uses of CMP_SEMANTIC for IP addresses

From legacy/trac#24546 (moved) comment 1:

We should also audit all uses of tor_addr_compare(a1, a2, CMP_EXACT) to see if they should be CMP_SEMANTIC instead. The current uses of CMP_SEMANTIC seem reasonable, but not essential: they code would still work if we rejected mapped addresses and did exact comparisons instead.