Simplify the way we achieve printing the error message when using the old API

Signed-off-by: Gergely Nagy <algernon@keyboard.io>

src/Kaleidoscope/MagicCombo.h

@@ -50,14 +50,9 @@ class MagicCombo : public kaleidoscope::Plugin {
   typedef struct combo_t {
     uint32_t left_hand, right_hand;
 
-    template <typename T>
-    struct always_false {
-      enum { value = false };
-    };
-
     template <typename T>
     combo_t(T l, T r) {
-      static_assert(always_false<T>::value, _DEPRECATE(_MAGICCOMBO_API_CHANGE));
+      static_assert(sizeof(T) < 0, _DEPRECATE(_MAGICCOMBO_API_CHANGE));
     }
   } combo_t;