Now, the gem5 implementation equals the Bochs variant. Note that its
necessary to enable CONFIG_EVENTS_BREAKPOINTS_RANGE in order to use
range breakpoints.
In addition, gem5 distinguishes between macro- and microops. With the
new implemenation, onBreakpoint is only called when a macroop changes.
Change-Id: Ib86d1802fc70c20d22ca1a1ece0e8d1221b2e7db