Default XRay building to OFF to let build bots that do not support building sanitizers to disable explicitly too
Default XRay building to OFF to let build bots that do not support building sanitizers to disable explicitly too

git-svn-id: c199f293c43da69278bea8e88f92242bf3aa95f7@276255 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