Remove Drop-caused migration-added captures

All of these were added due to insignificant Drop types being present.

src/librustdoc/doctest.rs

@@ -964,7 +964,6 @@ fn add_test(&mut self, test: String, config: LangString, line: usize) {
                 test_type: test::TestType::DocTest,
             },
             testfn: test::DynTestFn(Box::new(move || {
-                let _ = &config;
                 let report_unused_externs = |uext| {
                     unused_externs.lock().unwrap().push(uext);
                 };

src/tools/clippy/clippy_utils/src/lib.rs

@@ -990,10 +990,7 @@ fn visit_pat(&mut self, p: &'tcx Pat<'tcx>) {
         captures: HirIdMap::default(),
     };
     v.visit_expr(expr);
-    v.allow_closure.then(|| {
-        let _ = &v;
-        v.captures
-    })
+    v.allow_closure.then(|| v.captures)
 }
 
 /// Returns the method names and argument list of nested method call expressions that make up