Merge #7029

7029: Flush stdout when clearing the progress bar r=lnicola a=lnicola

To prevent this from happening:

```
Database loaded 496.24ms, 288mi
Crates in this dir: 1
Total modules found: 14
Total declarations: 159
Total functions: 122
Item Collection: 6.02s, 61846mi
122/122 100% processing: archive::sizeTotal expressions: 6592
Expressions of unknown type: 4 (0%)
Expressions of partially unknown type: 104 (1%)
Type mismatches: 3
Inference: 1.03s, 8622mi
Total: 7.05s, 70468mi
```

Co-authored-by: Laurențiu Nicola <lnicola@dend.ro>