Add a "fork" of musl as //fusl.

fusl/src/network/recvmmsg.c

Index: fusl/src/network/recvmmsg.c
diff --git a/fusl/src/network/recvmmsg.c b/fusl/src/network/recvmmsg.c
new file mode 100644
index 0000000000000000000000000000000000000000..58b1b2f635bdeba487f361acc9f0cc3a75e018aa
--- /dev/null
+++ b/fusl/src/network/recvmmsg.c
@@ -0,0 +1,15 @@
+#define _GNU_SOURCE
+#include <sys/socket.h>
+#include <limits.h>
+#include "syscall.h"
+
+int recvmmsg(int fd, struct mmsghdr *msgvec, unsigned int vlen, unsigned int flags, struct timespec *timeout)
+{
+#if LONG_MAX > INT_MAX
+	struct mmsghdr *mh = msgvec;
+	unsigned int i;
+	for (i = vlen; i; i--, mh++)
+		mh->msg_hdr.__pad1 = mh->msg_hdr.__pad2 = 0;
+#endif
+	return syscall_cp(SYS_recvmmsg, fd, msgvec, vlen, flags, timeout);
+}