In Liftoff, bugs often happen only if specific cache states are
constructed. For this, longer sequences of instructions are needed.
Thus, add a few rules to increase the chance of generating longer
sequences.

R=ahaas@chromium.org

Change-Id: I8f112edf0280282bf275585e8a15772013c25245
Reviewed-on: https://chromium-review.googlesource.com/1158695Reviewed-by: Andreas Haas <ahaas@chromium.org>
Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#54927}