Add Predictor Latency + Refactor cond pred out of BPredUnit

[shadowcpy]

This PR introduces the following changes:

• Fix a memory leak in the FDP packet processing logic (by @dhschall), supersedes cpu: fix bac memory leak (by @dhschall) #6
• Add latency modeling to the BAC stage, configurable with the new bacBranchPredictDelay param in the O3 CPU
• Split out the conditional branch predictor from BPredUnit into its own ConditionalPredictor, and update all predictor implementations to derive from the new class instead

Migration process for config scripts

To adapt the changes in your configuration, change code that looks like this:

class BPTageSCL(TAGE_SC_L_64KB):
    indirectBranchPred = ITTAGE()
    # ... other attributes

to this:

class BPTageSCL(BranchPredictor):
    indirectBranchPred = ITTAGE()
    conditionalBranchPred = TAGE_SC_L_64KB()
    # ... other attributes