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/simplicial_cholesky.cpp

@@ -39,7 +39,7 @@ template<typename T, typename I> void test_simplicial_cholesky_T()
   check_sparse_spd_solving(ldlt_colmajor_upper_nat, (std::min)(300,EIGEN_TEST_MAX_SIZE), 1000);
 }
 
-void test_simplicial_cholesky()
+EIGEN_DECLARE_TEST(simplicial_cholesky)
 {
   CALL_SUBTEST_1(( test_simplicial_cholesky_T<double,int>() ));
   CALL_SUBTEST_2(( test_simplicial_cholesky_T<std::complex<double>, int>() ));