Remove span from UpvarCapture::ByValue

This span is unused and is superseded by capture_kind_expr_id in CaptureInfo

compiler/rustc_middle/src/ty/closure.rs

@@ -56,13 +56,7 @@ pub enum UpvarCapture<'tcx> {
     /// Upvar is captured by value. This is always true when the
     /// closure is labeled `move`, but can also be true in other cases
     /// depending on inference.
-    ///
-    /// If the upvar was inferred to be captured by value (e.g. `move`
-    /// was not used), then the `Span` points to a usage that
-    /// required it. There may be more than one such usage
-    /// (e.g. `|| { a; a; }`), in which case we pick an
-    /// arbitrary one.
-    ByValue(Option<Span>),
+    ByValue,
 
     /// Upvar is captured by reference.
     ByRef(UpvarBorrow<'tcx>),