pythonGH-111485: Silence warnings in Python/executor_cases.c.h (python#111619)

Author: gvanrossum

Python/bytecodes.c

@@ -1216,6 +1216,8 @@ dummy_func(
             STAT_INC(UNPACK_SEQUENCE, deferred);
             DECREMENT_ADAPTIVE_COUNTER(this_instr[1].cache);
             #endif  /* ENABLE_SPECIALIZATION */
+            (void)seq;
+            (void)counter;
         }
 
         op(_UNPACK_SEQUENCE, (seq -- unused[oparg])) {