misc: fixed a perfcct error when pc greater than 0x80000000.

[zephyrols]

pc is unsigned, but sqlite3 only supports signed integer [-2^63, 2^63-1], if real pc > 2^63-1, it will be stored as negative number, (negtive pc = real pc - 2^64), when read a negtive pc, real pc = negtive pc + 2^64.

[zephyrols]

A script util/ClockAnalysis.py was added.

usage: ClockAnalysis.py [-h] [-p PERIOD] [-P {gem5,rtl}] [-s START_TICK] [-e END_TICK]
                        [-n NUM_INSTS] [--inter-gap] [--inner-gap] [--tool {perfcct,bbl}]
                        [--attention-pc ATTENTION_PC [ATTENTION_PC ...]]
                        [--start-pc START_PC] [--end-pc END_PC]
                        sqldb

positional arguments:
  sqldb                 Path to the SQLite database

options:
  -h, --help            show this help message and exit
  -p PERIOD, --period PERIOD
                        Number of ticks per clock cycle
  -P {gem5,rtl}, --platform {gem5,rtl}
                        Platform to analyze
  -s START_TICK, --start-tick START_TICK
                        Start tick to analyze
  -e END_TICK, --end-tick END_TICK
                        End tick to analyze
  -n NUM_INSTS, --num-insts NUM_INSTS
                        MAX Number of instructions to analyze
  --inter-gap           Analyze inter-gap
  --inner-gap           Analyze inner-gap
  --tool {perfcct,bbl}  Mode to analyze
  --attention-pc ATTENTION_PC [ATTENTION_PC ...]
                        Attention PC
  --start-pc START_PC   Start PC to analyze, a hex value start with 0x
  --end-pc END_PC       End PC to analyze, a hex value start with 0x