Re-add <experimental/coroutine> to the module map.

The original issues were caused because <experimental/coroutine>
didn't correctly #ifdef out enough of the header, which caused incomplete
types to be used.

This patch fixes the `#if defined(__cpp_coroutines)` guard and re-adds
the headers to the module map.

It also uglifies some incorrectly non-reserved names.

llvm-svn: 303936
Cr-Mirrored-From: sso://chromium.googlesource.com/_direct/external/github.com/llvm/llvm-project
Cr-Mirrored-Commit: ea96891fb42866d099188d014169ab147217d4ef
diff --git a/include/module.modulemap b/include/module.modulemap
index ad765c0..462d423 100644
--- a/include/module.modulemap
+++ b/include/module.modulemap
@@ -501,12 +501,10 @@
       header "experimental/chrono"
       export *
     }
-    // FIXME: This module only works when -fcoroutines-ts is enabled and it
-    // breaks the modules build otherwise.
-    // module coroutine {
-    //  header "experimental/coroutine"
-    //  export *
-    // }
+     module coroutine {
+      header "experimental/coroutine"
+      export *
+    }
     module deque {
       header "experimental/deque"
       export *