Fix #67131: setcookie() conditional for empty values not met

PHP applies a workaround for old MSIE where setting an empty cookie value would
not delete the cookie. This workaround is only triggered if an empty string (or
a value that converts to an empty string) is actually given as $value parameter
of setcookie. If the $value parameter is omitted, an empty cookie value is
sent. This commit fixes the inconsistent behavior.

ext/standard/head.c

@@ -110,7 +110,7 @@ PHPAPI int php_setcookie(char *name, int name_len, char *value, int value_len, t
 
 	cookie = emalloc(len + 100);
 
-	if (value && value_len == 0) {
+	if (value == NULL || value_len == 0) {
 		/*
 		 * MSIE doesn't delete a cookie when you set it to a null value
 		 * so in order to force cookies to be deleted, even on MSIE, we

ext/standard/tests/network/setcookie.phpt

@@ -6,6 +6,7 @@ date.timezone=UTC
 --FILE--
 <?php
 setcookie('name');
+setcookie('name', '');
 setcookie('name', 'value');
 setcookie('name', 'space value');
 setcookie('name', 'value', 0);
@@ -19,7 +20,8 @@ setcookie('name', 'value', 0, '', '', FALSE, TRUE);
 
 
 $expected = array(
-	'Set-Cookie: name=',
+	'Set-Cookie: name=deleted; expires='.date('D, d-M-Y H:i:s', 1).' GMT; Max-Age=0',
+	'Set-Cookie: name=deleted; expires='.date('D, d-M-Y H:i:s', 1).' GMT; Max-Age=0',
 	'Set-Cookie: name=value',
 	'Set-Cookie: name=space+value',
 	'Set-Cookie: name=value',
@@ -64,6 +66,7 @@ while (next($headers) !== FALSE);
 echo ($i === 0)
 	? 'OK'
 	: 'A total of '.$i.' errors found.';
+?>
 --EXPECTHEADERS--
 
 --EXPECT--