cpu: Fix a bug in counting issued instructions in MinorCPU
cpu: Fix a bug in counting issued instructions in MinorCPU

The MinorCPU would count bubbles in Execute::issue as part of
the num_insts_issued and so sometimes reach the instruction
issue limit incorrectly.

Fixed by checking for a bubble in one new place.
(transplanted from a50657a4f0c1820972632fff4b508b607e4c2367)

andrewfu0325/gem5-aladdin,andrewfu0325/gem5-aladdin,andrewfu0325/gem5-aladdin,andrewfu0325/gem5-aladdin,andrewfu0325/gem5-aladdin,andrewfu0325/gem5-aladdin,andrewfu0325/gem5-aladdin