Ports: Add libuv

We've had a half-arsed port of libuv inside the cmake port, but let's
just port it properly.
Note that this pins a specific commit (which is currently the latest
commit in their default branch).

Ports/libuv/patches/0004-tcp-Don-t-use-SO_LINGER.patch

@@ -0,0 +1,36 @@
+From 91c2345d42459232d958eaf0eba5b10786ac3475 Mon Sep 17 00:00:00 2001
+From: Ali Mohammad Pur <ali.mpfard@gmail.com>
+Date: Fri, 9 Jul 2021 04:59:05 +0430
+Subject: [PATCH 4/7] tcp: Don't use SO_LINGER
+
+---
+ src/unix/tcp.c | 4 ++++
+ 1 file changed, 4 insertions(+)
+
+diff --git a/src/unix/tcp.c b/src/unix/tcp.c
+index bc0fb66..e78259a 100644
+--- a/src/unix/tcp.c
++++ b/src/unix/tcp.c
+@@ -313,15 +313,19 @@ int uv_tcp_getpeername(const uv_tcp_t* handle,
+ 
+ int uv_tcp_close_reset(uv_tcp_t* handle, uv_close_cb close_cb) {
+   int fd;
++#ifndef __serenity__
+   struct linger l = { 1, 0 };
++#endif
+ 
+   /* Disallow setting SO_LINGER to zero due to some platform inconsistencies */
+   if (handle->flags & UV_HANDLE_SHUTTING)
+     return UV_EINVAL;
+ 
+   fd = uv__stream_fd(handle);
++#ifndef __serenity__
+   if (0 != setsockopt(fd, SOL_SOCKET, SO_LINGER, &l, sizeof(l)))
+     return UV__ERR(errno);
++#endif
+ 
+   uv_close((uv_handle_t*) handle, close_cb);
+   return 0;
+-- 
+2.32.0
+