Merge third_party/usrsctp/usrsctplib from https://chromium.googlesource.com/external/usrsctplib.git at 7accb99da6264405fd546d98af91e4f2969002c5

This commit was generated by merge_from_chromium.py.

Change-Id: Ib579411cf6bde8b41afdb9dc185a6658dc7c7d4f