Force $binaryPrefixes array ordering on 32-bit systems, fixes #83

[Forst]

This fixes an issue when a 32-bit system breaks associative array ordering when dropping keys over 2^32-1 in String\BinarySuffix and String\MetricSuffix

As noted by @mikaelcom, the following array:

private $binaryPrefixes = array(
    1125899906842624 => '#.## PB',
    1099511627776 => '#.## TB',
    1073741824 => '#.## GB',
    1048576 => '#.## MB',
    1024 => '#.# kB',
    0 => '# bytes',
);

in String\BinarySuffix becomes:

array(4) {
    [0] =>
    string(7) "# bytes"
    [1073741824] =>
    string(7) "#.## GB"
    [1048576] =>
    string(7) "#.## MB"
    [1024] =>
    string(6) "#.# kB"
}

during runtime on 32-bit systems. This breaks the conversion logic, causing a Division by zero exception.

The introduced change sorts the associative array with krsort() so that it gets ordered properly:

array(4) {
    [1073741824] =>
    string(7) "#.## GB"
    [1048576] =>
    string(7) "#.## MB"
    [1024] =>
    string(6) "#.# kB"
    [0] =>
    string(7) "# bytes"
}

Tested on: Ubuntu 14.04.5, kernel 4.4.0-42-generic i686, PHP 5.5.9-1ubuntu4.20.

Should be tested on other architectures and with other values, but I don't think there are any negative consequences to this change.

[norberttech]

Awesome 👍 🍻