Updating xcode config. (#2198)

Changing the xcode platform to just `Native`. This lets xcode handle
all the target stuff, and works regardless of target.

scripts/genie.lua

@@ -122,9 +122,9 @@ solution "bgfx"
 		"Release",
 	}
 
-	if _ACTION ~= nil and _ACTION:match "xcode*" then
+	if _ACTION ~= nil and _ACTION:match "^xcode" then
 		platforms {
-			"Universal",
+			"Native", -- let xcode decide based on the target output
 		}
 	else
 		platforms {