Travis: build matrix improvements + CPP11 build

src/unittest/test_threading.cpp

@@ -163,6 +163,7 @@ class AtomicTestThread : public Thread {
 void TestThreading::testAtomicSemaphoreThread()
 {
 	Atomic<u32> val;
+	val = 0;
 	Semaphore trigger;
 	static const u8 num_threads = 4;