[XRay][compiler-rt] Only run custom event logging in x86_64-linux
We only have an implementation in x86_64 that works for the
patching/unpatching and runtime support (trampolines).
Follow-up to D30630.
//
// RUN: %clangxx_xray -std=c++11 %s -o %t
// RUN: XRAY_OPTIONS="patch_premain=false verbosity=1 xray_naive_log=false xray_logfile_base=custom-event-logging.xray-" %run %t 2>&1 | FileCheck %s
-//
+// FIXME: Support this in non-x86_64 as well
+// REQUIRES: x86_64-linux
+// REQUIRES: built-in-llvm-tree
#include <cstdio>
#include "xray/xray_interface.h"
