[XRay] Remove the unused variable

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

llvm-svn: 342320

compiler-rt/test/xray/TestCases/Posix/fdr-single-thread.cc

@@ -16,8 +16,6 @@
 [[clang::xray_always_instrument]] void __attribute__((noinline)) fn() { }
 
 int main(int argc, char *argv[]) {
-  FDRLoggingOptions Opts;
-
   auto status = __xray_log_init_mode("xray-fdr", "");
   assert(status == XRayLogInitStatus::XRAY_LOG_INITIALIZED);