Description:
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mysqlnd makes PHP segfault on connect.

This bug is filed as "PDO", but it's really a mysqlnd bug. The issue is the same regardless of what extension is used: PDO, MySQL or MySQLi. PHP was compiled from CVS, with --with-mysql=mysqlnd --with-mysqli=mysqlnd --with-pdo-mysql=mysqlnd

- Connecting via TCP or socket does not change the behaviour.
- It doesn't require a valid account either, attempting to connect with an inexistent account produces the same result.
- It does require a valid DSN, otherwise a PDOException with message 'SQLSTATE[HY000] [2002] Connection refused' is thrown, as expected.

Backtrace below, if you need anything else please ask. Thanks :)

Reproduce code:
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$db = new PDO('mysql:dbname=test;host=127.0.0.1;port=3307', 'inexistent_user', 'password');

Actual result:
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#0  0x000000000075d729 in mysqlnd_connect (conn=0xece3c8, host=0xece288 "127.0.0.1", user=0xece160 "inexistent_user", passwd=0xece1c8 "password",
    passwd_len=8, db=0xece228 "test", db_len=4, port=3307, socket=0x0, mysql_flags=196736, zval_cache=0xea0c50)
    at /root/src/php5/ext/mysqlnd/mysqlnd.c:823
#1  0x000000000058475a in pdo_mysql_handle_factory (dbh=0xecdbc0, driver_options=0x0) at /root/src/php5/ext/pdo_mysql/mysql_driver.c:717
#2  0x00000000005739c7 in zim_PDO_dbh_constructor (ht=3, return_value=0xece068, return_value_ptr=0x0, this_ptr=0xecc200, return_value_used=0)
    at /root/src/php5/ext/pdo/pdo_dbh.c:372
#3  0x000000000083a574 in zend_do_fcall_common_helper_SPEC (execute_data=0x2add638ad090) at /root/src/php5/Zend/zend_vm_execute.h:315
#4  0x000000000083b509 in ZEND_DO_FCALL_BY_NAME_SPEC_HANDLER (execute_data=0x2add638ad090) at /root/src/php5/Zend/zend_vm_execute.h:428
#5  0x00000000008395a7 in execute (op_array=0xeccfb0) at /root/src/php5/Zend/zend_vm_execute.h:104
#6  0x000000000080981e in zend_execute_scripts (type=8, retval=0x0, file_count=3) at /root/src/php5/Zend/zend.c:1197
#7  0x000000000078e21a in php_execute_script (primary_file=0x7fff472a8590) at /root/src/php5/main/main.c:2075
#8  0x00000000008ad1d4 in main (argc=2, argv=0x7fff472a8808) at /root/src/php5/sapi/cli/php_cli.c:1130