swift234

[PrintAsObjC] Mark 'internal(set)' properties as 'readonly' for frameworks.

"...because the generated header for a framework is part of the framework's
public Objective-C interface, only declarations marked public appear in the
generated header for a Swift framework."

Just missed a case here when we decided to do things this way.

<rdar://problem/17796727>

Swift SVN r20653