[LNT] Python 3 support: encode LNT report format in UTF-8

Summary:
Change encoding of LNT report format to be a UTF-8 JSON file since that
is the only encoding the json module can produce in Python 3. While this
is an incompatible change of the output, the existing import of LNT
report format already expects UTF-8 JSON. Therefore this fixes an import
issue for format produced from there and does not change anything for
already produced format which could not be imported and still cannot be
imported.

Reviewers: cmatthews, hubert.reinterpretcast, kristof.beyls

Reviewed By: hubert.reinterpretcast

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D68225

llvm-svn: 373218

Author: Thomas Preud'homme

lnt/testing/__init__.py

@@ -93,12 +93,12 @@ def render(self, indent=4):
                                'machine': self.machine.render(),
                                'run': self.run.render(),
                                'tests': [t.render() for t in self.tests]},
-                              sort_keys=True, indent=indent, encoding='latin-1')
+                              sort_keys=True, indent=indent)
         else:
             return json.dumps({'Machine': self.machine.render(),
                                'Run': self.run.render(),
                                'Tests': [t.render() for t in self.tests]},
-                              sort_keys=True, indent=indent, encoding='latin-1')
+                              sort_keys=True, indent=indent)
 
 
 class Machine: