SILGen: Fix the logic of dynamic replacements for class constructors

To correctly call designated super class initializers the designated
intializer (and not the allocator) is dynamically replaceable.
Convenience allocators are dynamically replaceable as before.

lib/SIL/SILFunctionBuilder.cpp

@@ -86,7 +86,7 @@ void SILFunctionBuilder::addFunctionAttributes(SILFunction *F,
     return;
   }
 
-  if (constant.isInitializerOrDestroyer())
+  if (!constant.canBeDynamicReplacement())
     return;
 
   SILDeclRef declRef(replacedDecl, constant.kind, false);