[vm/fuzzer] Fix reproduction output
[vm/fuzzer] Fix reproduction output

Rationale:
Add space between fp and seed parameter. Check whether generate variable
is set in TestRunnerKBC.
Change-Id: I3f1b21b65e75286d2ca560d9fa8c05ed3e4e5f55
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/116542
Reviewed-by: Aart Bik <293afa0533434225484ba3f9bf2859340baba6ea@google.com>
Commit-Queue: Felicitas Hetzelt <dd58ecf83e6dafb983e3eceed132b302900c5729@google.com>

dartino/dart-sdk,dartino/dart-sdk,dart-lang/sdk,dart-archive/dart-sdk,dart-lang/sdk,dartino/dart-sdk,dart-archive/dart-sdk,dart-lang/sdk,dart-archive/dart-sdk,dart-archive/dart-sdk,dart-lang/sdk,dart-archive/dart-sdk,dart-archive/dart-sdk,dartino/dart-sdk,dart-lang/sdk,dart-archive/dart-sdk,dart-lang/sdk,dart-lang/sdk,dartino/dart-sdk,dartino/dart-sdk,dart-archive/dart-sdk,dart-archive/dart-sdk,dartino/dart-sdk,dart-lang/sdk,dartino/dart-sdk,dartino/dart-sdk