Make empty_fcall_info_cache a macro

See php#18273, a constant may cause
unnecessary cache misses.

Author: iluuu1994

Zend/zend_API.h

@@ -691,7 +691,12 @@ ZEND_API zend_result _call_user_function_impl(zval *object, zval *function_name,
 	_call_user_function_impl(object, function_name, retval_ptr, param_count, params, named_params)
 
 ZEND_API extern const zend_fcall_info empty_fcall_info;
-ZEND_API extern const zend_fcall_info_cache empty_fcall_info_cache;
+
+#ifndef __cplusplus
+# define empty_fcall_info_cache (zend_fcall_info_cache) {0}
+#else
+# define empty_fcall_info_cache zend_fcall_info_cache {0}
+#endif
 
 /** Build zend_call_info/cache from a zval*
  *
@@ -800,7 +805,7 @@ static zend_always_inline void zend_fcc_dtor(zend_fcall_info_cache *fcc)
 	if (fcc->closure) {
 		OBJ_RELEASE(fcc->closure);
 	}
-	memcpy(fcc, &empty_fcall_info_cache, sizeof(zend_fcall_info_cache));
+	*fcc = empty_fcall_info_cache;
 }
 
 ZEND_API void zend_get_callable_zval_from_fcc(const zend_fcall_info_cache *fcc, zval *callable);

Zend/zend_execute_API.c

@@ -55,7 +55,6 @@ ZEND_API zend_class_entry *(*zend_autoload)(zend_string *name, zend_string *lc_n
 
 /* true globals */
 ZEND_API const zend_fcall_info empty_fcall_info = {0};
-ZEND_API const zend_fcall_info_cache empty_fcall_info_cache = {0};
 
 #ifdef ZEND_WIN32
 ZEND_TLS HANDLE tq_timer = NULL;