Bring back the test-suite export in test-release without bringing back the build...

Bring back the test-suite export in test-release without bringing back the build failures.

Summary:
r257791 disabled the test-suite export since the addition of CMakeLists.txt was
causing build failures. This patch exports the test-suite again but does so
outside the source tree so that it isn't included in the Phase[123] builds.

Reviewers: hans

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D16679

git-svn-id: https://llvm.org/svn/llvm-project/llvm/branches/release_38@259093 91177308-0d34-0410-b5e6-96231b3b80d8