Description:
------------
preg_match returns errors while parsing some correct expressions, o dies with apache if there is more such "errors"...

The same behaviour is both in 4.4.2 and 5.1.2

Reproduce code:
---------------
$expressions = array(
1 => '/^ (?: . ){0,6} $/ix',
2 => '/^ (?: . ){0, 6} $/ix',
3 => '/^ (?: . ) {0, 6} $/ix',
4 => '/^ (?: . ) {0,6} $/ix',
);

foreach ($expressions as $key => $exp) {
    echo $key, ": ";
    var_dump(preg_match($exp, '2', $pat));
    var_dump($pat);
    echo "\n";
}


Expected result:
----------------
1: int(1)
array(1) {
  [0]=>
  string(1) "2"
}

2: int(1)
array(1) {
  [0]=>
  string(1) "2"
}

3: int(1)
array(1) {
  [0]=>
  string(1) "2"
}

4: int(1)
array(1) {
  [0]=>
  string(1) "2"
}


Actual result:
--------------
1: int(1)
array(1) {
  [0]=>
  string(1) "2"
}

2: int(0)
array(0) {
}

3: int(0)
array(0) {
}

4: Warning: preg_match(): Compilation failed: internal error: code overflow at offs
et 17 in D:\Inetpub\Projects\.php5\testrx.php on line 12
bool(false)
array(0) {
}
... or sometimes there is no 4: ... and apache dies...