[ValueObject] Do not return address of eValueTypeHostAddress values.

Summary:
This fixes TestRegisterVariables for clang and hence it is enabled in this commit.


Test Plan: dotest.py -C clang -p TestRegisterVariables

Reviewers: clayborg

Reviewed By: clayborg

Subscribers: lldb-commits

Differential Revision: http://reviews.llvm.org/D9421

llvm-svn: 236447