[infra] Use unbuffered I/O for run_recipe

This probably makes very little difference, but it might be helpful in
certain situations to see the unbuffered raw output.

Change-Id: Id0adf77ab3a8d0221d6dc8b7aea39fe9785b03dd
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/261137
Commit-Queue: Eric Boren <borenet@google.com>
Auto-Submit: Ben Wagner aka dogben <benjaminwagner@google.com>
Reviewed-by: Eric Boren <borenet@google.com>
2 files changed