Bug 1468928 - Unbreak build without GeckoProfiler after bug 1405374. r=mstange

In file included from objdir/js/xpconnect/src/Unified_cpp_js_xpconnect_src1.cpp:110:
js/xpconnect/src/nsXPConnect.cpp:76:37: error: use of undeclared identifier
      'profiler_register_thread'
    JS::SetProfilingThreadCallbacks(profiler_register_thread, profiler_unregister_thread);
                                    ^
js/xpconnect/src/nsXPConnect.cpp:76:63: error: use of undeclared identifier
      'profiler_unregister_thread'
    JS::SetProfilingThreadCallbacks(profiler_register_thread, profiler_unregister_thread);
                                                              ^

MozReview-Commit-ID: HrBGEkByEum

--HG--
extra : rebase_source : b588e8f04d44d07c348120efc6008e6c24b8949e

js/xpconnect/src/nsXPConnect.cpp

@@ -73,7 +73,9 @@ nsXPConnect::nsXPConnect()
 {
     XPCJSContext::InitTLS();
 
+#ifdef MOZ_GECKO_PROFILER
     JS::SetProfilingThreadCallbacks(profiler_register_thread, profiler_unregister_thread);
+#endif
 
     XPCJSContext* xpccx = XPCJSContext::NewXPCJSContext(nullptr);
     if (!xpccx) {