Auto merge of #102692 - nnethercote:TokenStreamBuilder, r=Aaron1011

Remove `TokenStreamBuilder`

`TokenStreamBuilder` is used to combine multiple token streams. It can be removed, leaving the code a little simpler and a little faster.

r? `@Aaron1011`

Author: bors

proc_macro/src/bridge/client.rs

@@ -223,10 +223,10 @@ pub(crate) use super::symbol::Symbol;
 
 macro_rules! define_client_side {
     ($($name:ident {
-        $(fn $method:ident($($arg:ident: $arg_ty:ty),* $(,)?) $(-> $ret_ty:ty)*;)*
+        $(fn $method:ident($($arg:ident: $arg_ty:ty),* $(,)?) $(-> $ret_ty:ty)?;)*
     }),* $(,)?) => {
         $(impl $name {
-            $(pub(crate) fn $method($($arg: $arg_ty),*) $(-> $ret_ty)* {
+            $(pub(crate) fn $method($($arg: $arg_ty),*) $(-> $ret_ty)? {
                 Bridge::with(|bridge| {
                     let mut buf = bridge.cached_buffer.take();