aircrack-ptw-lib: optimize integer sort helpers
aircrack-ptw-lib: use conditional instead of mod in rc4init()
aircrack-ptw-lib: use 32-bit ints for rc4 state

This change allows the compiler to achieve better optimizations.
~24% speedup for 32- and 64-bit x86.
aircrack-ptw-lib: split correct() to simplify future optimizations
aircrack-ptw-lib: amd64 SSE2-optimized rc4test()

~10% faster than gcc-generated SSE2 optimizations.