Rename lots of files that had generator in their name

tests/ui/async-await/coroutine-desc.rs

@@ -0,0 +1,16 @@
+// edition:2018
+#![feature(async_closure)]
+use std::future::Future;
+
+async fn one() {}
+async fn two() {}
+
+fn fun<F: Future<Output = ()>>(f1: F, f2: F) {}
+fn main() {
+    fun(async {}, async {});
+    //~^ ERROR mismatched types
+    fun(one(), two());
+    //~^ ERROR mismatched types
+    fun((async || {})(), (async || {})());
+    //~^ ERROR mismatched types
+}