Disable hymap deduction guide for old GCCs

Author: fthaler

include/gridtools/common/hymap.hpp

@@ -198,8 +198,10 @@ namespace gridtools {
             template <class...>
             struct values;
 
+#if defined(__clang__) || (defined(__GNUC__) && __GNUC__ >= 11)
             template <class... Vs>
             values(Vs const &...) -> values<Vs...>;
+#endif
 
             // NVCC 11 fails to do class template deduction in the case of nested templates
             template <class... Args>

tests/unit_tests/common/test_hymap.cpp

@@ -96,7 +96,7 @@ namespace gridtools {
             EXPECT_EQ(7.3, at_key<b>(dst));
         }
 
-#if !defined(__NVCC__)
+#if defined(__clang__) || (defined(__GNUC__) && __GNUC__ >= 11)
         TEST(deduction, smoke) {
             auto testee = hymap::keys<a, b>::values(42, 5.3);