Hide the symbols exported by the FreeType API See https://github.com/flutter/flutter/issues/106118 Change-Id: Iceebe722e6c61c0e7b7af01e86c317ec2bda0f9f Bug: 106118 Reviewed-on: https://flutter-review.googlesource.com/c/third_party/freetype2/+/31480 Reviewed-by: Chinmay Garde <chinmaygarde@google.com> Commit-Queue: Jason Simmons <jsimmons@google.com>