Add missing 'requires coroutines' to module map

llvm-svn: 304180
Cr-Mirrored-From: sso://chromium.googlesource.com/_direct/external/github.com/llvm/llvm-project
Cr-Mirrored-Commit: a607ba6134491074fb9b848a391464e42a8c1eaf
diff --git a/include/module.modulemap b/include/module.modulemap
index 462d423..98b1870 100644
--- a/include/module.modulemap
+++ b/include/module.modulemap
@@ -502,6 +502,7 @@
       export *
     }
      module coroutine {
+      requires coroutines
       header "experimental/coroutine"
       export *
     }