fix 5 years old copy/paste error (patch by Mikko)

ext/curl/interface.c

@@ -1427,7 +1427,7 @@ static int _php_curl_setopt(php_curl *ch, long option, zval **zvalue, zval *retu
 		case CURLOPT_READFUNCTION:
 			if (ch->handlers->read->func_name) {
 				zval_ptr_dtor(&ch->handlers->read->func_name);
-				ch->handlers->write->fci_cache = empty_fcall_info_cache;
+				ch->handlers->read->fci_cache = empty_fcall_info_cache;
 			}
 			zval_add_ref(zvalue);
 			ch->handlers->read->func_name = *zvalue;
@@ -1436,7 +1436,7 @@ static int _php_curl_setopt(php_curl *ch, long option, zval **zvalue, zval *retu
 		case CURLOPT_HEADERFUNCTION:
 			if (ch->handlers->write_header->func_name) {
 				zval_ptr_dtor(&ch->handlers->write_header->func_name);
-				ch->handlers->write->fci_cache = empty_fcall_info_cache;
+				ch->handlers->write_header->fci_cache = empty_fcall_info_cache;
 			}
 			zval_add_ref(zvalue);
 			ch->handlers->write_header->func_name = *zvalue;