scripts/performance: Add dissect.py script

scripts/performance: Add dissect.py script

Python script that dissects QEMU execution into three main phases:
code generation, JIT execution and helpers execution.

Syntax:
dissect.py [-h] -- <qemu executable> [<qemu executable options>] \
                 <target executable> [<target executable options>]

[-h] - Print the script arguments help message.

Example of usage:
dissect.py -- qemu-arm coulomb_double-arm

Example output:
Total Instructions:        4,702,865,362

Code Generation:             115,819,309	 2.463%
JIT Execution:             1,081,980,528	23.007%
Helpers:                   3,505,065,525	74.530%

Signed-off-by: Ahmed Karaman <ahmedkhaledkaraman@gmail.com>
Reviewed-by: Aleksandar Markovic <aleksandar.qemu.devel@gmail.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Message-Id: <20200709052055.2650-2-ahmedkhaledkaraman@gmail.com>
Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>