[XRay] Remove the unused variable

This broke the fdr-single-thread test after FDRLoggingOptions struct
has been removed in r342318.

git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@342320 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed