tcpConnectToHost try all addresses in AddressList

The AddressList returned can contain more than one item
e.g. the ipv4 and ipv6 addresses for a given hostname.
Previously if a server had multiple addresses but
was not listening on one of them Zig would give up
immediately.

Now on std.os.ConnectError.ConnectionRefused Zig will
try the next address in the list. Zig still gives up on
all other errors as they are related to the system and
system resources rather than whether the remote server
is listening on a particular address.

lib/std/net.zig

@@ -573,7 +573,15 @@ pub fn tcpConnectToHost(allocator: *mem.Allocator, name: []const u8, port: u16)
 
     if (list.addrs.len == 0) return error.UnknownHostName;
 
-    return tcpConnectToAddress(list.addrs[0]);
+    for (list.addrs) |addr| {
+        return tcpConnectToAddress(addr) catch |err| switch (err) {
+            error.ConnectionRefused => {
+                continue;
+            },
+            else => return err,
+        };
+    }
+    return std.os.ConnectError.ConnectionRefused;
 }
 
 pub fn tcpConnectToAddress(address: Address) !fs.File {