docs: update docs for objc_storeStrong behaviour

objc_storeStrong does not return a value.

llvm-svn: 294855
diff --git a/clang/lib/CodeGen/CodeGenModule.h b/clang/lib/CodeGen/CodeGenModule.h
index 613e300..465d0b4 100644
--- a/clang/lib/CodeGen/CodeGenModule.h
+++ b/clang/lib/CodeGen/CodeGenModule.h
@@ -166,7 +166,7 @@
   /// void objc_release(id);
   llvm::Constant *objc_release;
 
-  /// id objc_storeStrong(id*, id);
+  /// void objc_storeStrong(id*, id);
   llvm::Constant *objc_storeStrong;
 
   /// id objc_storeWeak(id*, id);