This patch fixes an issue where, when printing corefile notes with
llvm-readobj as json, the dumper generated llvm formatted output which
isn't valid json. This alters the dumper to, in the NT_FILE, note, dump
properly formatted json data.
Prior to this patch the JSON output was formatted like:
```
"Mapping": [
"Start": 4096,
"End": 8192,
"Offset": 12288,
"Filename": "/path/to/a.out"
],
```
Whereas now it is formatted as:
```
"Mappings": [
{
"Start": 4096,
"End": 8192,
"Offset": 12288,
"Filename": "/path/to/a.out"
},
```
Which is valid. Additionally the LLVM output has changed to match the
structure of the JSON output (i.e. instead of lists of keys it is a list
of dictionaries)
942a6af6ad