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

test/array_for_matrix.cpp

@@ -256,7 +256,7 @@ void regrrssion_bug_1410()
   VERIFY((internal::traits<MatrixWrapper<Array4i> >::Flags&LvalueBit)==LvalueBit);
 }
 
-void test_array_for_matrix()
+EIGEN_DECLARE_TEST(array_for_matrix)
 {
   for(int i = 0; i < g_repeat; i++) {
     CALL_SUBTEST_1( array_for_matrix(Matrix<float, 1, 1>()) );