Description:
------------
As unixODBC functions are not async-signal-safe, nor safe to be longjmp'ed out, If a timeout occurs during an odbc calls, with a lock set, the PHP script will hangs.

I have a patch proposal, will submit a pull request.

Test script:
---------------
<?php
ini_set('max_execution_time', '1');
$db = odbc_connect('MySQL-test', 'root', '');
if (!$db) {
    print "failed to connect\n";
} else {
    while(true) {
	echo ".";
        $result = odbc_exec($db, 'SELECT * FROM mysql.user');
    }
}


Expected result:
----------------
$ php test.php
.............................................................................
.............................................................................
.............................................................................
.............................................................................
.............................................................................
....PHP Fatal error:  Maximum execution time of 1 second exceeded in /home/rcollet/git/php/php/Regression/bz594813-ODBC-execution-timeout-hang/bz594813.php on line 10
$ 

Actual result:
--------------
Same output, but script hangs, need to be killed.