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/product_syrk.cpp

@@ -117,7 +117,7 @@ template<typename MatrixType> void syrk(const MatrixType& m)
                    ((s1 * m1.row(c).adjoint() * m1.row(c).adjoint().adjoint()).eval().template triangularView<Upper>().toDenseMatrix()));
 }
 
-void test_product_syrk()
+EIGEN_DECLARE_TEST(product_syrk)
 {
   for(int i = 0; i < g_repeat ; i++)
   {