Roll buildroot to 6669621484b649b9355fb2dd37950daf3d2ac65b (#18652)

flutter/buildroot@6669621484b649b9355fb2dd37950daf3d2ac65b

See flutter/buildroot#372
https://dart.googlesource.com/external/github.com/flutter/engine/+/c5d012900f7db0dc5dc9afb46f76d16b87915db0
1 file changed
tree: 93600320ee8fee795417c7e98e0306f31cb9bd7a
  1. commits.json