explicitly mark coroutine closures.

This is required with rust-lang/rust#123792

Author: soooch

Diff for: effing-macros/src/lib.rs

@@ -155,6 +155,7 @@ pub fn effectful(args: TokenStream, item: TokenStream) -> TokenStream {
             Yield = #yield_type,
             Return = #return_type
         > #clone_bound {
+            #[coroutine]
             move |_begin: <#yield_type as ::effing_mad::injection::EffectList>::Injections| {
                 #block
             }

Diff for: src/lib.rs

@@ -111,6 +111,7 @@ pub fn map<E, I, T, U>(
     g: impl Coroutine<I, Yield = E, Return = T>,
     f: impl FnOnce(T) -> U,
 ) -> impl Coroutine<I, Yield = E, Return = U> {
+    #[coroutine]
     static move |mut injs: I| {
         let mut pinned = pin!(g);
         loop {
@@ -207,6 +208,7 @@ where
     PostIs: CoproductEmbedder<PreIs, EmbedIndices>,
     G: Coroutine<PreIs, Yield = PreEs, Return = R>,
 {
+    #[coroutine]
     static move |_begin: PostIs| {
         let mut injection = PreIs::inject(Begin);
         let mut pinned = pin!(g);
@@ -342,6 +344,7 @@ where
         > + CoproductSubsetter<HandlerIs, SubsetIndices2>,
     G1: Coroutine<PreIs, Yield = PreEs, Return = R>,
 {
+    #[coroutine]
     static move |_begin: PostIs| {
         let mut injection = PreIs::inject(Begin);
         let mut pinned = pin!(g);