[coroutines] Fix assertion during -Wuninitialized analysis

Summary: @rsmith Is there a better place to put this test?

Reviewers: GorNishanov, rsmith

Reviewed By: GorNishanov

Subscribers: cfe-commits, rsmith

Differential Revision: https://reviews.llvm.org/D33660

llvm-svn: 304331
diff --git a/clang/lib/Sema/SemaCoroutine.cpp b/clang/lib/Sema/SemaCoroutine.cpp
index ae6c35f..f5594bd 100644
--- a/clang/lib/Sema/SemaCoroutine.cpp
+++ b/clang/lib/Sema/SemaCoroutine.cpp
@@ -437,6 +437,7 @@
   if (VD->isInvalidDecl())
     return nullptr;
   ActOnUninitializedDecl(VD);
+  FD->addDecl(VD);
   assert(!VD->isInvalidDecl());
   return VD;
 }