Description:
------------
The fix for bug #27172 (possible floating-point 
exception in gmp_powm) breaks the function with modulos 
longer than 31 bits.  This is because the modulo 
argument is converted (destructively) to a long before 
it is fetched as a GMP number.  The problem is rectified 
by moving the block that checks for a zero modulo to a 
point after the argument is fetched for use in the 
function.

I have posted a diff here:

http://oscar.the-rileys.net/php5-gpm_powm-patch.diff

I have tested this on my own server, and it appears to 
fix the problem with at least 1024-bit modulos and still 
guards against 0 modulos - test for yourself to be sure, 
of course,

Reproduce code:
---------------
This is the example code from the documentation page for gpm_powm:

<?php
?? $pow1 = gmp_powm("2", "31", "2147483649");
?? echo gmp_strval($pow1) . "\n";
?>

Expected result:
----------------
The number 2147483648 should be output.

Actual result:
--------------
The number 1 is output.