diff -up mozilla-beta/xpcom/threads/ThreadStackHelper.cpp.rt-tgsigqueueinfo mozilla-beta/xpcom/threads/ThreadStackHelper.cpp

--- mozilla-beta/xpcom/threads/ThreadStackHelper.cpp.rt-tgsigqueueinfo	2015-04-16 23:45:29.000000000 +0200

+++ mozilla-beta/xpcom/threads/ThreadStackHelper.cpp	2015-04-22 09:10:25.291166226 +0200

@@ -240,10 +240,13 @@ ThreadStackHelper::GetStack(Stack& aStac

   uinfo.si_pid = getpid();

   uinfo.si_uid = getuid();

   uinfo.si_value.sival_ptr = this;

+#ifdef SYS_rt_tgsigqueueinfo

   if (::syscall(SYS_rt_tgsigqueueinfo, uinfo.si_pid,

-                mThreadID, sFillStackSignum, &uinfo)) {

+                mThreadID, sFillStackSignum, &uinfo))

     // rt_tgsigqueueinfo was added in Linux 2.6.31.

     // Could have failed because the syscall did not exist.

+#endif

+  {

     return;

   }

   MOZ_ALWAYS_TRUE(!::sem_wait(&mSem));