Features: Fix test to reject missing expectation definitions

Whenever feature support is added to a compiler, the CompileFeatures
test needs to be updated to set expected availability of features.
Add #error directives to ensure the test fails if expectations are
not set.

Suggested-by: Stephen Kelly <[email protected]>

Tests/CompileFeatures/genex_test.cpp

@@ -1,3 +1,15 @@
+#ifndef EXPECT_FINAL
+# error EXPECT_FINAL not defined
+#endif
+#ifndef EXPECT_INHERITING_CONSTRUCTORS
+# error EXPECT_INHERITING_CONSTRUCTORS not defined
+#endif
+#ifndef EXPECT_INHERITING_CONSTRUCTORS_AND_FINAL
+# error EXPECT_INHERITING_CONSTRUCTORS_AND_FINAL not defined
+#endif
+#ifndef EXPECT_OVERRIDE_CONTROL
+# error EXPECT_OVERRIDE_CONTROL not defined
+#endif
 
 #if !HAVE_OVERRIDE_CONTROL
 #if EXPECT_OVERRIDE_CONTROL