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/0003-stream-Don-t-use-AF_INET6.patch

@@ -0,0 +1,37 @@
+From 774eb9413fb32bc3656ddcd9ccb22af3d2083278 Mon Sep 17 00:00:00 2001
+From: Ali Mohammad Pur <ali.mpfard@gmail.com>
+Date: Fri, 9 Jul 2021 04:57:31 +0430
+Subject: [PATCH 3/7] stream: Don't use AF_INET6
+
+---
+ src/unix/stream.c | 8 +++++++-
+ 1 file changed, 7 insertions(+), 1 deletion(-)
+
+diff --git a/src/unix/stream.c b/src/unix/stream.c
+index f64c01c..96f6417 100644
+--- a/src/unix/stream.c
++++ b/src/unix/stream.c
+@@ -995,13 +995,19 @@ uv_handle_type uv__handle_type(int fd) {
+       case AF_UNIX:
+         return UV_NAMED_PIPE;
+       case AF_INET:
++#ifndef __serenity__
+       case AF_INET6:
++#endif
+         return UV_TCP;
+       }
+   }
+ 
+   if (type == SOCK_DGRAM &&
+-      (ss.ss_family == AF_INET || ss.ss_family == AF_INET6))
++      (ss.ss_family == AF_INET
++#ifndef __serenity__
++       || ss.ss_family == AF_INET6
++#endif
++    ))
+     return UV_UDP;
+ 
+   return UV_UNKNOWN_HANDLE;
+-- 
+2.32.0
+