Update nativesockets.nim, namelen should be the len of name (#24810)

In other places where `getsockname` is called, the size of the 'name' is
used.

d573578b28/lib/pure/nativesockets.nim (L347-L351)

d573578b28/lib/pure/nativesockets.nim (L585-L595)

d573578b28/lib/pure/nativesockets.nim (L622-L624)

d573578b28/lib/pure/nativesockets.nim (L347-L350)

I have checked the [Windows
documentation](https://learn.microsoft.com/en-us/windows/win32/api/winsock2/nf-winsock2-getsockname#remarks),
and it describes it like this: "On call, the namelen parameter contains
the size of the name buffer, in bytes. On return, the namelen parameter
contains the actual size in bytes of the name parameter."

[https://www.man7.org/linux/man-pages/man2/getsockname.2.html](https://www.man7.org/linux/man-pages/man2/getsockname.2.html)
say:
The addrlen argument should be initialized to indicate the amount of
space (in bytes) pointed to by addr.

(cherry picked from commit 8e36fb0fec)

lib/pure/nativesockets.nim

@@ -723,7 +723,7 @@ when useNimNetLite:
     ##
     ## Similar to POSIX's `getsockname`:idx:.
     template sockGetNameOrRaiseError(socket: untyped, name: untyped) =
-      var namelen = sizeof(socket).SockLen
+      var namelen = sizeof(name).SockLen
       if getsockname(socket, cast[ptr SockAddr](addr(name)),
                     addr(namelen)) == -1'i32:
         raiseOSError(osLastError())