std.os.linux: adding recvmmsg() (#22651)

lib/std/os/linux.zig

@@ -1878,6 +1878,17 @@ pub fn recvmsg(fd: i32, msg: *msghdr, flags: u32) usize {
     }
 }
 
+pub fn recvmmsg(fd: i32, msgvec: ?[*]mmsghdr, vlen: u32, flags: u32, timeout: ?*timespec) usize {
+    return syscall5(
+        .recvmmsg,
+        @as(usize, @bitCast(@as(isize, fd))),
+        @intFromPtr(msgvec),
+        vlen,
+        flags,
+        @intFromPtr(timeout),
+    );
+}
+
 pub fn recvfrom(
     fd: i32,
     noalias buf: [*]u8,