SFENCE - Throughput and Uops

With unroll_count=500 and no inner loop

Code:
```
   0:	0f ae f8             	sfence 
```
Show nanoBench command
Results:
- Instructions retired: 1.0
- Core cycles: 9.0
- Reference cycles: 9.0
- RS_UOPS_DISPATCHED: 2.0
- UOPS_PORT_0: 0.0
- UOPS_PORT_1: 0.0
- UOPS_PORT_2: 0.0
- UOPS_PORT_3: 1.0
- UOPS_PORT_4: 1.0
- UOPS_PORT_5: 0.0

With loop_count=1000 and unroll_count=10

Code:
```
   0:	0f ae f8             	sfence 
```
Show nanoBench command
Results:
- Instructions retired: 1.2
- Core cycles: 8.9
- Reference cycles: 8.9
- RS_UOPS_DISPATCHED: 2.2
- UOPS_PORT_0: 0.0
- UOPS_PORT_1: 0.0
- UOPS_PORT_2: 0.0
- UOPS_PORT_3: 1.0
- UOPS_PORT_4: 1.0
- UOPS_PORT_5: 0.2

With loop_count=100 and unroll_count=100

Code:
```
   0:	0f ae f8             	sfence 
```
Show nanoBench command
Results:
- Instructions retired: 1.02
- Core cycles: 8.99
- Reference cycles: 8.99
- RS_UOPS_DISPATCHED: 2.02
- UOPS_PORT_0: 0.0
- UOPS_PORT_1: 0.0
- UOPS_PORT_2: 0.0
- UOPS_PORT_3: 1.0
- UOPS_PORT_4: 1.0
- UOPS_PORT_5: 0.02