Made sure that ValueObjectVariable actually
updates itself before it tries to set its own
data.  Otherwise it has no idea where to put the
data value.

<rdar://problem/15846476>


git-svn-id: https://llvm.org/svn/llvm-project/lldb/trunk@199533 91177308-0d34-0410-b5e6-96231b3b80d8