Adds handling of page-spanning instruction fetch and data accesses. For offline traces these are heuristics as we do not know the precise sizes at tracing time. Since an extra physical page value is not harmful, the heuristics emit a second page if there is any decent change that it is reached.
Adds a data page span test by switching the drcacheoff.phys test to use allasm_repstr and adding such an access there. An instruction cross is more difficult to synthesize.
Issue: #4014