Include tests only if COMPILER_RT_BUILD_XRAY is ON.
Include tests only if COMPILER_RT_BUILD_XRAY is ON.

This should un-break users that have not re-generated their CMake
configs when they ran it when this was defaulted to OFF. Related to
r277975 post-commit review.

git-svn-id: c199f293c43da69278bea8e88f92242bf3aa95f7@279802 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