`printf`: extra spaces if padding number is not next to %

Cases: 
```
printf "% -3.0f" 1
 1 %
cargo run printf "% -3.0f" 1
 1  %(extra spaces here)
cargo run printf '%-3.0f' 1`
1  %

printf "% 3.0d" 1
 1 %
cargo run printf "% 3.0d" 1
 1  %(extra spaces here)
```

However, if the number is negative, the space will be filled with `-`, then there's no extra padding:
```
cargo run printf "% -3.0f" -1
-1 %
```

related issue: #2774 