Description:
------------
php configured --with-pdo-dblib=shared,/usr

After fetch first (any) resultset PDOStatement::nextRowset() cause segmentation fault instead of return boolean result.

Segfault reproduced with php 5.4.41, 5.5.25, 5.6.9; freetds: 0.91, 0.95rc3


Test script:
---------------
<?php

if (!extension_loaded('pdo_dblib')) {
    die('skip not loaded');
}
require __DIR__ . '/config.inc';

$sql = "
EXEC sp_executesql N'
    SELECT 1 as first_rowset
    SELECT 2 as second_rowset
'
"; 
//$sql = 'SELECT 1 as first_rowset'; // same result: segfault
$stmt = $db->query($sql);

$resultset1 = $stmt->fetchAll(PDO::FETCH_ASSOC);
//var_dump($resultset1); // first_rowset => 1
$stmt->nextRowset(); //segfault here



Actual result:
--------------
Core was generated by `php pdo_dblib_next_rowset_segfault.php'.
Program terminated with signal SIGSEGV, Segmentation fault.
#0  0x000000000067c6d8 in zend_mm_check_ptr (heap=0x1493b20, ptr=0x16f2308, silent=1, 
    __zend_filename=0x7f1e5d148c08 "/tmp/php-5.6.9/ext/pdo/pdo_stmt.c", __zend_lineno=2053, __zend_orig_filename=0x0, 
    __zend_orig_lineno=0) at /tmp/php-5.6.9/Zend/zend_alloc.c:1384
1384            if (p->info._size != ZEND_MM_NEXT_BLOCK(p)->info._prev) {
(gdb) bt
#0  0x000000000067c6d8 in zend_mm_check_ptr (heap=0x1493b20, ptr=0x16f2308, silent=1, 
    __zend_filename=0x7f1e5d148c08 "/tmp/php-5.6.9/ext/pdo/pdo_stmt.c", __zend_lineno=2053, __zend_orig_filename=0x0, 
    __zend_orig_lineno=0) at /tmp/php-5.6.9/Zend/zend_alloc.c:1384
#1  0x000000000067e2d2 in _zend_mm_free_int (heap=0x1493b20, p=0x16f2308, 
    __zend_filename=0x7f1e5d148c08 "/tmp/php-5.6.9/ext/pdo/pdo_stmt.c", __zend_lineno=2053, __zend_orig_filename=0x0, 
    __zend_orig_lineno=0) at /tmp/php-5.6.9/Zend/zend_alloc.c:2068
#2  0x000000000067f75c in _efree (ptr=0x16f2308, __zend_filename=0x7f1e5d148c08 "/tmp/php-5.6.9/ext/pdo/pdo_stmt.c", 
    __zend_lineno=2053, __zend_orig_filename=0x0, __zend_orig_lineno=0) at /tmp/php-5.6.9/Zend/zend_alloc.c:2440
#3  0x00007f1e5d1441d7 in pdo_stmt_do_next_rowset (stmt=0x7f1e61a76ad0) at /tmp/php-5.6.9/ext/pdo/pdo_stmt.c:2053
#4  0x00007f1e5d144333 in zim_PDOStatement_nextRowset (ht=0, return_value=0x7f1e61a77960, return_value_ptr=0x7f1e64250200, 
    this_ptr=0x7f1e61a76c90, return_value_used=0) at /tmp/php-5.6.9/ext/pdo/pdo_stmt.c:2082
#5  0x00000000006fd188 in zend_do_fcall_common_helper_SPEC (execute_data=0x7f1e642503b8)
    at /tmp/php-5.6.9/Zend/zend_vm_execute.h:558
#6  0x00000000006fd95c in ZEND_DO_FCALL_BY_NAME_SPEC_HANDLER (execute_data=0x7f1e642503b8)
    at /tmp/php-5.6.9/Zend/zend_vm_execute.h:693
#7  0x00000000006fc7f1 in execute_ex (execute_data=0x7f1e642503b8) at /tmp/php-5.6.9/Zend/zend_vm_execute.h:363
#8  0x00000000006fc87a in zend_execute (op_array=0x7f1e6428cf30) at /tmp/php-5.6.9/Zend/zend_vm_execute.h:388
#9  0x00000000006b9058 in zend_execute_scripts (type=8, retval=0x0, file_count=3) at /tmp/php-5.6.9/Zend/zend.c:1341
#10 0x00000000006242af in php_execute_script (primary_file=0x7ffd72f96120) at /tmp/php-5.6.9/main/main.c:2597
#11 0x000000000076ad09 in do_cli (argc=2, argv=0x1493870) at /tmp/php-5.6.9/sapi/cli/php_cli.c:994
#12 0x000000000076be16 in main (argc=2, argv=0x1493870) at /tmp/php-5.6.9/sapi/cli/php_cli.c:1378