Change the version number of the feature

Author: frank-king

compiler/rustc_feature/src/active.rs

@@ -582,7 +582,7 @@ declare_features! (
     /// Enables rustc to generate code that instructs libstd to NOT ignore SIGPIPE.
     (active, unix_sigpipe, "1.65.0", Some(97889), None),
     /// Allows unnamed fields of struct and union type
-    (incomplete, unnamed_fields, "1.68.0", Some(49804), None),
+    (incomplete, unnamed_fields, "CURRENT_RUSTC_VERSION", Some(49804), None),
     /// Allows unsized fn parameters.
     (active, unsized_fn_params, "1.49.0", Some(48055), None),
     /// Allows unsized rvalues at arguments and parameters.