std.event.tcp: add switch statement in preparation for building-out abstractions;

depends on issue #1274 ;

std/event/tcp.zig

@@ -123,10 +123,17 @@ pub async fn connect(loop: *Loop, _address: *const std.net.Address) !std.os.File
 }
 
 test "listen on a port, send bytes, receive bytes" {
-    if (builtin.os != builtin.Os.linux) {
-        // TODO build abstractions for other operating systems
+    // TODO build abstractions for other operating systems
+    const skip_test: bool = switch (builtin.os) {
+        builtin.Os.linux => false,
+        //builtin.Os.macosx, builtin.Os.ios => false,
+        else => true,
+    };
+
+    if (skip_test == true) {
         return error.skip;
     }
+
     const MyServer = struct {
         tcp_server: Server,