Merge third_party/usrsctp/usrsctplib from https://chromium.googlesource.com/external/usrsctplib.git at dfd687bb8ef6224a1e3c38a7de9e79e854b142ad

This commit was generated by merge_from_chromium.py.

Change-Id: If72e0e4ae1dc864d34a51f51cbd44a9c56c57b1f