This is a PHP mt_rand() seed cracker.  It finds possible seeds given the
very first mt_rand() output after being seeded with mt_srand().

Here's a sample run.  First, generate a sample "random" number (using
PHP 5.3.x in this case):

$ php5 -r 'mt_srand(1234567890); echo mt_rand(), "\n";'
1328851649

Now build and run the cracker:

$ make
gcc -Wall -march=native -O2 -fomit-frame-pointer -funroll-loops -fopenmp php_mt_seed.c -o php_mt_seed
$ time ./php_mt_seed 1328851649
Found 0, trying 637534208 - 671088639, speed 63310249 seeds per second
seed = 658126103
Found 1, trying 1207959552 - 1241513983, speed 63343447 seeds per second
seed = 1234567890
Found 2, trying 4261412864 - 4294967295, speed 63347894 seeds per second
Found 2

real    1m7.798s
user    9m1.942s
sys     0m0.008s

In one minute of real time (on an FX-8120 CPU, using vectorized fused
multiply-add instructions), it found the original seed, another seed
that also produces the same mt_rand() output, and it searched the rest
of the 32-bit seed space (not finding other matches).
