Internally, we started running into a build failure after r321774 with the following error: "use of undeclared identifier 'mmsghdr'." The underlying issue is that we have machines that are using an older version of glibc, glibc 2.11.3, which don't define mssghdr. I would love to upgrade these machines, but unfortunately that's currently not an option.
This patch just checks for the mmsghdr feature prior to trying to intercept sendmmsg/recvmmsg. Feedback is very much welcome as this is not my area of expertise.