[xray] Fix CMake for X-RAY tests
[xray] Fix CMake for X-RAY tests

Correctly depend on llvm-xray, make sure unit tests are being run.

Differential Revision: https://reviews.llvm.org/D38917

git-svn-id: c199f293c43da69278bea8e88f92242bf3aa95f7@315827 91177308-0d34-0410-b5e6-96231b3b80d8

llvm-mirror/compiler-rt,llvm-mirror/compiler-rt,llvm-mirror/compiler-rt,llvm-mirror/compiler-rt,llvm-mirror/compiler-rt