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

unsupported/test/minres.cpp

@@ -36,7 +36,7 @@ template<typename T> void test_minres_T()
 
 }
 
-void test_minres()
+EIGEN_DECLARE_TEST(minres)
 {
   CALL_SUBTEST_1(test_minres_T<double>());
 //  CALL_SUBTEST_2(test_minres_T<std::compex<double> >());