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/geo_eulerangles.cpp

@@ -103,7 +103,7 @@ template<typename Scalar> void eulerangles()
   check_all_var(ea);
 }
 
-void test_geo_eulerangles()
+EIGEN_DECLARE_TEST(geo_eulerangles)
 {
   for(int i = 0; i < g_repeat; i++) {
     CALL_SUBTEST_1( eulerangles<float>() );