Merge third_party/usrsctp/usrsctplib from https://chromium.googlesource.com/external/usrsctplib.git at 8975bd5397c2ec97f50e0b87b544054e0536bfe1

This commit was generated by merge_from_chromium.py.

Change-Id: Id51cb6df777cd692b0a5e93b7b7fb741bbbe125a