Deactivate optimizations for this test file when using clang

The file is a bit complex to compile and clang hangs quite a lot
during the optimization process (>1h and not compiled yet!).

tests/test_EmbeddedIDiscreteFunctionOperators.cpp

@@ -185,6 +185,10 @@
     REQUIRE(is_same);                                                            \
   }
 
+#ifdef __clang__
+#pragma clang optimize off
+#endif   // __clang__
+
 TEST_CASE("EmbeddedIDiscreteFunctionOperators", "[scheme]")
 {
   SECTION("binary operators")
@@ -2716,3 +2720,7 @@ TEST_CASE("EmbeddedIDiscreteFunctionOperators", "[scheme]")
     }
   }
 }
+
+#ifdef __clang__
+#pragma clang optimize on
+#endif   // __clang__