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

fusl/src/network/socketpair.c

Index: fusl/src/network/socketpair.c
diff --git a/fusl/src/network/socketpair.c b/fusl/src/network/socketpair.c
new file mode 100644
index 0000000000000000000000000000000000000000..f3489621139a9d2deb5ee3f30eca76ecbec1fe4d
--- /dev/null
+++ b/fusl/src/network/socketpair.c
@@ -0,0 +1,25 @@
+#include <sys/socket.h>
+#include <fcntl.h>
+#include <errno.h>
+#include "syscall.h"
+
+int socketpair(int domain, int type, int protocol, int fd[2])
+{
+	int r = socketcall(socketpair, domain, type, protocol, fd, 0, 0);
+	if (r<0 && (errno==EINVAL || errno==EPROTONOSUPPORT)
+	    && (type&(SOCK_CLOEXEC|SOCK_NONBLOCK))) {
+		r = socketcall(socketpair, domain,
+			type & ~(SOCK_CLOEXEC|SOCK_NONBLOCK),
+			protocol, fd, 0, 0);
+		if (r < 0) return r;
+		if (type & SOCK_CLOEXEC) {
+			__syscall(SYS_fcntl, fd[0], F_SETFD, FD_CLOEXEC);
+			__syscall(SYS_fcntl, fd[1], F_SETFD, FD_CLOEXEC);
+		}
+		if (type & SOCK_NONBLOCK) {
+			__syscall(SYS_fcntl, fd[0], F_SETFL, O_NONBLOCK);
+			__syscall(SYS_fcntl, fd[1], F_SETFL, O_NONBLOCK);
+		}
+	}
+	return r;
+}