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_meta.cpp

@@ -340,7 +340,7 @@ static void test_array_misc()
   VERIFY_IS_EQUAL((instantiate_by_c_array<dummy_inst, int, 5>(data).c), 5);
 }
 
-void test_cxx11_meta()
+EIGEN_DECLARE_TEST(cxx11_meta)
 {
   CALL_SUBTEST(test_gen_numeric_list());
   CALL_SUBTEST(test_concat());