Small accept4 fixes.

Put the accept4 test in the sorted order, and put the accept4 define in
sorted order.

Also add the missing SYS_RECVMMSG and SYS_SENDMMSG defines.

Change-Id: Iba55354975e0d5027dbee53f6de752c2df719493
diff --git a/libc/include/sys/socket.h b/libc/include/sys/socket.h
index 5001b2e..86fd3cf 100644
--- a/libc/include/sys/socket.h
+++ b/libc/include/sys/socket.h
@@ -284,6 +284,7 @@
 #endif
 
 __socketcall int accept(int, struct sockaddr*, socklen_t*);
+__socketcall int accept4(int, struct sockaddr*, socklen_t*, int);
 __socketcall int bind(int, const struct sockaddr*, int);
 __socketcall int connect(int, const struct sockaddr*, socklen_t);
 __socketcall int getpeername(int, struct sockaddr*, socklen_t*);
@@ -298,7 +299,6 @@
 __socketcall int shutdown(int, int);
 __socketcall int socket(int, int, int);
 __socketcall int socketpair(int, int, int, int*);
-__socketcall int accept4(int, struct sockaddr*, socklen_t*, int);
 
 extern ssize_t send(int, const void*, size_t, int);
 extern ssize_t recv(int, void*, size_t, int);