[Clippy] Swap manual_retain to use diagnostic items instead of paths

compiler/rustc_span/src/symbol.rs

@@ -488,6 +488,7 @@ symbols! {
         begin_panic,
         bench,
         bin,
+        binaryheap_iter,
         bind_by_move_pattern_guards,
         bindings_after_at,
         bitand,
@@ -511,6 +512,7 @@ symbols! {
         breakpoint,
         bridge,
         bswap,
+        btreeset_iter,
         builtin_syntax,
         c,
         c_str,
@@ -971,6 +973,7 @@ symbols! {
         half_open_range_patterns,
         half_open_range_patterns_in_slices,
         hash,
+        hashset_iter,
         hexagon_target_feature,
         hidden,
         homogeneous_aggregate,
@@ -1077,6 +1080,9 @@ symbols! {
         item,
         item_like_imports,
         iter,
+        iter_cloned,
+        iter_copied,
+        iter_filter,
         iter_mut,
         iter_repeat,
         iterator,
@@ -1817,6 +1823,7 @@ symbols! {
         slice,
         slice_from_raw_parts,
         slice_from_raw_parts_mut,
+        slice_iter,
         slice_len_fn,
         slice_patterns,
         slicing_syntax,
@@ -1849,6 +1856,7 @@ symbols! {
         stop_after_dataflow,
         store,
         str,
+        str_chars,
         str_from_utf8,
         str_from_utf8_mut,
         str_from_utf8_unchecked,
@@ -2064,6 +2072,7 @@ symbols! {
         variant_count,
         vec,
         vec_macro,
+        vecdeque_iter,
         version,
         vfp2,
         vis,