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/is_same_dense.cpp

@@ -11,7 +11,7 @@
 
 using internal::is_same_dense;
 
-void test_is_same_dense()
+EIGEN_DECLARE_TEST(is_same_dense)
 {
   typedef Matrix<double,Dynamic,Dynamic,ColMajor> ColMatrixXd;
   typedef Matrix<std::complex<double>,Dynamic,Dynamic,ColMajor> ColMatrixXcd;