Include AddLLVM needed for tests in the right context

AddLLVM is needed for several functions that are used in tests and
as such needs to be included from the right context which previously
wasn't the case.

Differential Revision: https://reviews.llvm.org/D40280

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@319515 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed