Use zend_empty_array

No need to define our own `com_dotnet_object_properties` as empty hash,
since we can use `zend_empty_array` instead as of PHP 7.3.0.

Cf. <#3672 (comment)>.

Author: cmb69

ext/com_dotnet/com_extension.c

@@ -293,8 +293,6 @@ PHP_MINIT_FUNCTION(com_dotnet)
 {
 	zend_class_entry ce, *tmp;
 
-	zend_hash_init(&com_dotnet_object_properties, 0, NULL, NULL, 0);
-
 	php_com_wrapper_minit(INIT_FUNC_ARGS_PASSTHRU);
 	php_com_persist_minit(INIT_FUNC_ARGS_PASSTHRU);
 

ext/com_dotnet/com_handlers.c

@@ -27,8 +27,6 @@
 #include "php_com_dotnet_internal.h"
 #include "Zend/zend_exceptions.h"
 
-const HashTable com_dotnet_object_properties;
-
 static zval *com_property_read(zval *object, zval *member, int type, void **cahce_slot, zval *rv)
 {
 	php_com_dotnet_object *obj;
@@ -231,7 +229,7 @@ static HashTable *com_properties_get(zval *object)
 	 * infinite recursion when the hash is displayed via var_dump().
 	 * Perhaps it is best to leave it un-implemented.
 	 */
-	return &com_dotnet_object_properties;
+	return &zend_empty_array;
 }
 
 static void function_dtor(zval *zv)

ext/com_dotnet/php_com_dotnet_internal.h

@@ -29,8 +29,6 @@
 
 #include "zend_ts_hash.h"
 
-extern const HashTable com_dotnet_object_properties;
-
 typedef struct _php_com_dotnet_object {
 	zend_object zo;