drcachesim post-processing can incorrectly abort on a filtered buffer-final one-of-multi-memref

When using a drcachesim online-filtered trace (-L0_filter), a multi-memref instruction can have one of its memrefs hit in the cache and the other miss. The post-processor will then expect 2 addresses but only have 1. Today we recognize this and skip the other in the middle of a buffer, but at the end we incorrectly report an error "Trace ends mid-block".