printf:output doesn't match with GNU printf

# About

The uutils output doesn't match the GNU printf output

```
 cargo run -- printf "%g" -0.1171875
-0.11719       
         
cargo run -- printf "%g"  -0.00001
-0.00001                    
```

vs

```
printf "%g" -0.1171875
-0.117188                  

printf "%g"  -0.00001
-1e-05                                       
```

This was discovered during work on #6959 