[modules] Remove IRGen special case for emitting implicit special members if
they're somehow missing a body. Looks like this was left behind when the loop
was generalized, and it's not been problematic before because without modules,
a used, implicit special member function declaration must be a definition.

This was resulting in us trying to emit a constructor declaration rather than
a definition, and producing a constructor missing its member initializers.

llvm-svn: 214473
diff --git a/clang/lib/CodeGen/CGClass.cpp b/clang/lib/CodeGen/CGClass.cpp
index 9427de1..920a071 100644
--- a/clang/lib/CodeGen/CGClass.cpp
+++ b/clang/lib/CodeGen/CGClass.cpp
@@ -711,7 +711,9 @@
     return;
   }
 
-  Stmt *Body = Ctor->getBody();
+  const FunctionDecl *Definition = 0;
+  Stmt *Body = Ctor->getBody(Definition);
+  assert(Definition == Ctor && "emitting wrong constructor body");
 
   // Enter the function-try-block before the constructor prologue if
   // applicable.