Description:
------------
zend_print_flat_zval_r and zend_print_zval_r_ex doesn't consider reference in php 7.0.x.

The following error may be triggered：
PHP Notice:  Array to string conversion;
Catchable fatal error: Object could not be converted to string.

This bug has been fixed in php 7.1, why php 7.0.x is not fixed.

Test script:
---------------
$a = array('a');
class b{};
$b = new b;
$test[] =& $a;
$test[] =& $b;
test($test);
function test() {
    debug_print_backtrace();
}


Expected result:
----------------
#0  test(Array ([0] => Array ([0] => a),[1] => b Object ())) called at [/Users/playcrab/Documents/code/php/test/test7.php:7]

Actual result:
--------------
#0  test(Array ([0] => PHP Notice:  Array to string conversion in /Users/playcrab/Documents/code/php/test/test7.php on line 9
PHP Stack trace:
PHP   1. {main}() /Users/playcrab/Documents/code/php/test/test7.php:0
PHP   2. test() /Users/playcrab/Documents/code/php/test/test7.php:7
PHP   3. debug_print_backtrace() /Users/playcrab/Documents/code/php/test/test7.php:9
PHP Catchable fatal error:  Object of class b could not be converted to string in /Users/playcrab/Documents/code/php/test/test7.php on line 9
PHP Stack trace:
PHP   1. {main}() /Users/playcrab/Documents/code/php/test/test7.php:0
PHP   2. test() /Users/playcrab/Documents/code/php/test/test7.php:7
PHP   3. debug_print_backtrace() /Users/playcrab/Documents/code/php/test/test7.php:9

Notice: Array to string conversion in /Users/playcrab/Documents/code/php/test/test7.php on line 9

Call Stack:
    0.0068     353088   1. {main}() /Users/playcrab/Documents/code/php/test/test7.php:0
    0.0080     353928   2. test() /Users/playcrab/Documents/code/php/test/test7.php:7
    0.0080     353928   3. debug_print_backtrace() /Users/playcrab/Documents/code/php/test/test7.php:9

Array,[1] => 
Catchable fatal error: Object of class b could not be converted to string in /Users/playcrab/Documents/code/php/test/test7.php on line 9

Call Stack:
    0.0068     353088   1. {main}() /Users/playcrab/Documents/code/php/test/test7.php:0
    0.0080     353928   2. test() /Users/playcrab/Documents/code/php/test/test7.php:7
    0.0080     353928   3. debug_print_backtrace() /Users/playcrab/Documents/code/php/test/test7.php:9