Use logger.warning() instead of logger.info() on instrumentation crash

We need at least "warning" level to see logs from worker threads.

Change-Id: I4ec5d9d89f5697cf5710a250888e054789716f78
Reviewed-on: https://chrome-internal-review.googlesource.com/c/v8/fuzzilli/+/9151416
Commit-Queue: Leon Bettscheider <bettscheider@google.com>
Reviewed-by: Matthias Liedtke <mliedtke@google.com>
Reviewed-by: Michael Achenbach <machenbach@google.com>

Author: lebe-g

Sources/Fuzzilli/Mutators/RuntimeAssistedMutator.swift

@@ -129,15 +129,15 @@ public class RuntimeAssistedMutator: Mutator {
 
                 let execution = fuzzer.execute(mutatedProgram, withTimeout: fuzzer.config.timeout , purpose: .runtimeAssistedMutation)
                 if case .crashed(let signal) = execution.outcome {
-                    logger.info("Mutated program crashed as well, reporting mutated program instead")
+                    logger.warning("Mutated program crashed as well, reporting mutated program instead")
                     let stdout = execution.fuzzout + "\n" + execution.stdout
                     fuzzer.processCrash(mutatedProgram, withSignal: signal, withStderr: execution.stderr, withStdout: stdout, origin: .local, withExectime: execution.execTime)
                     return failure(.instrumentedProgramCrashed)
                 }
             }
 
             // If we reach here, the process()'d program did not crash, so we need to report the instrumented program.
-            logger.info("Mutated program did not crash, reporting original crash of the instrumented program")
+            logger.warning("Mutated program did not crash, reporting original crash of the instrumented program")
             fuzzer.processCrash(instrumentedProgram, withSignal: signal, withStderr: oldStderr, withStdout: stdout, origin: .local, withExectime: execution.execTime)
         case .succeeded:
             // The expected case.