<rdar://problem/11239650> Fixing a bug where the SetValueFromCString() method...

<rdar://problem/11239650> Fixing a bug where the SetValueFromCString() method failed to operate on dynamic values. The fix consists in making the set operation fall through to the parent. We only actually allow this if the dynamic value is at a 0-offset from the parent, or the new value is 0. Other scenarios would need agreement on the actual meaning of the set operation (do we keep offsetting? do we just assume the user knows what they are doing?) so we prevent them, and let the expression parser deal with the complexity

llvm-svn: 156422