mark getPrevVMState as UNSAFE

Summary: This function can break all sorts of assumptions the JIT makes and crash HHVM. Lets put a little barrier into the mind of a person using it.

The common and safe use is to just get the previous Func*.

Reviewed By: @jdelong

Differential Revision: D1638947
add option to make iconv actually match the docs

Summary: On the docs http://php.net/manual/en/function.iconv.php they give this example:

```
<?php
$text = "This is the Euro symbol '€'.";

echo 'Original : ', $text, PHP_EOL;
echo 'TRANSLIT : ', iconv("UTF-8", "ISO-8859-1//TRANSLIT", $text), PHP_EOL;
echo 'IGNORE   : ', iconv("UTF-8", "ISO-8859-1//IGNORE", $text), PHP_EOL;
echo 'Plain    : ', iconv("UTF-8", "ISO-8859-1", $text), PHP_EOL;

?>
```

which should output

```
Original : This is the Euro symbol '€'.
TRANSLIT : This is the Euro symbol 'EUR'.
IGNORE   : This is the Euro symbol ''.
Plain    :
Notice: iconv(): Detected an illegal character in input string in .\iconv-example.php on line 7
This is the Euro symbol '
```

but if you run it on PHP http://3v4l.org/k615V the `//IGNORE` case is broken.

I think what the docs say is best, and looks the most sane, so lets make the language better.

Reviewed By: @paulbiss

Differential Revision: D1646046

Signature: t1:1646046:1414598441:eeb6befb62a8beec215df76d134a036f45589f9f
Fixed iconv() error behaviour - take 2

Summary: This reverts commit 4faec5261e6adfea81e8e66379470d71b24976fd.

With D1646046 we can keep the better //IGNORE behaviour

Reviewed By: @paulbiss

Differential Revision: D1646155

Signature: t1:1646155:1414598669:f7d88607ceda773350dbb1a14c2e61b1ab616dd0
move binary ignores into hphp

Summary: We have the tree inverted internally so ignored things have to be in this dir instead of the root dir.

Reviewed By: @JoelMarcey

Differential Revision: D1646172

Signature: t1:1646172:1414598925:09a541432cf88fff354819670c87260b221d157d
move slow 'quick' tests to 'slow'

Summary: The minimum overhead for a test run is 0.8 seconds, so I made the cutoff at 2x that and moved anything over 1.6 seconds to slow/lang. One of the tests was obviously i18n so I moved that to test/slow/intl/

Timed with:

    for i in `ls -1 test/quick/*.php`; do echo -n "$i "; /usr/bin/time test/run $i 2>&1 | grep user | sed s/user.*//; done > /tmp/a

Reviewed By: @swtaarrs, @JoelMarcey, @bertmaher, @paulbiss, @jdelong

Differential Revision: D1639378