Get rid of EIGEN_TEST_FUNC, unit tests must now be declared with EIGEN_DECLARE_TEST(mytest) { /* code */ }.

This provide several advantages:
- more flexibility in designing unit tests
- unit tests can be glued to speed up compilation
- unit tests are compiled with same predefined macros, which is a requirement for zapcc

unsupported/test/cxx11_tensor_notification.cpp

@@ -65,7 +65,7 @@ static void test_notification_multiple()
   VERIFY_IS_EQUAL(counter, 4);
 }
 
-void test_cxx11_tensor_notification()
+EIGEN_DECLARE_TEST(cxx11_tensor_notification)
 {
   CALL_SUBTEST(test_notification_single());
   CALL_SUBTEST(test_notification_multiple());