Description:
------------
strrchr() function can't find the new line when an heredoc string containing only a blank line is given as input, whereas it works fine when the heredoc string containing regular string with new line.

This is noticed on php5 and php6.

Reproduce code:
---------------
<?php
$str1 = <<<EOD

EOD;

$str2 = <<<EOD
hello
hiiiiiii
EOD;

//doesn't work as expected
var_dump( strrchr($str1, $str1) );
var_dump( strrchr($str1, "\n") );
var_dump( strrchr($str1, "
") );

//works as expected
var_dump( strrchr($str2, "\n") );
var_dump( strrchr($str2, "
") );
?>


Expected result:
----------------
string(1) "
"
string(1) "
"
string(1) "
"
string(9) "
hiiiiiii"
string(9) "
hiiiiiii"


Actual result:
--------------
bool(false)
bool(false)
bool(false)
string(9) "
hiiiiiii"
string(9) "
hiiiiiii"