Fix --diagnostics
Fix --diagnostics

When enabled, ensureDeterministicExecutionOutcomeForDiagnostic would use the
stdout and stderr of the initial execution, which were, however, no longer
valid as new executions performed as part of deterministicCorpus had
already overwritten them.

googleprojectzero/fuzzilli,googleprojectzero/fuzzilli,googleprojectzero/fuzzilli