Initialize with contents in the Flutter buildroot.

Imported from https://github.com/flutter/buildroot/tree/430b57c643883e6090b5af09faddd8048efee57c.

Only an extra .gitignore has been added.

Change-Id: Ibca759b00d2d894e714ef5743b15bbc4c63086e4
Reviewed-on: https://flutter-review.googlesource.com/c/third_party/libxml/+/24223
Reviewed-by: Jason Simmons <jsimmons@google.com>
Commit-Queue: Chinmay Garde <chinmaygarde@google.com>
190 files changed