[tools] Fix typo in build.py
[tools] Fix typo in build.py

Closes https://github.com/dart-lang/sdk/pull/44580
https://github.com/dart-lang/sdk/pull/44580

GitOrigin-RevId: 43ebbcec6ee358d04f19bdd2850b2aa8f9718ad5
Change-Id: Ia10816097d43f9ee1062d846326a680767033165
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/177520
Reviewed-by: Vyacheslav Egorov <72c81f38df725d8f1832acb9b5bb99563fc2f1b9@google.com>
Commit-Queue: Vyacheslav Egorov <72c81f38df725d8f1832acb9b5bb99563fc2f1b9@google.com>

dart-lang/sdk,dart-lang/sdk,dart-lang/sdk,dart-lang/sdk,dart-lang/sdk,dart-lang/sdk,dart-lang/sdk,dart-lang/sdk