[llvm-readelf] --notes: move 'Data size' column left by 1

readelf -n:

```
// "Data size" is not left justified
  Owner                 Data size       Description
  GNU                  0x00000010       NT_GNU_ABI_TAG (ABI version tag)
```

llvm-readelf -n (before):
```
// "Data size" column shifted by 1
  Owner                 Data size        Description
  GNU                   0x00000010       NT_GNU_ABI_TAG (ABI version tag)
```

llvm-readelf -n (after):
```
  Owner                Data size        Description
  GNU                  0x00000010       NT_GNU_ABI_TAG (ABI version tag)
```

This change is made to reduce the diff with readelf -n, so that it is
slightly easier to check what features readelf implements but we don't.

Reviewed By: grimar, jhenderson

Differential Revision: https://reviews.llvm.org/D65847

llvm-svn: 368138