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/pastix_support.cpp

@@ -45,7 +45,7 @@ template<typename T> void test_pastix_T_LU()
   check_sparse_square_solving(pastix_lu);
 }
 
-void test_pastix_support()
+EIGEN_DECLARE_TEST(pastix_support)
 {
   CALL_SUBTEST_1(test_pastix_T<float>());
   CALL_SUBTEST_2(test_pastix_T<double>());