Fix for x64 build

This is small fix, as building x64 build would never build without .asm file which you have in other projects :)
I've included nmake makefile for building x64 version, feel free to include same in VC GUI if needed... 

You want to check "kost" branch of "shellcodeexec" as it have mingw support:
https://github.com/kost/shellcodeexec

Which means I can compile windows binaries using Linux/Mac and resulting binaries are much smaller (UPXed win32 is smaller than 4 kb):
https://github.com/kost/shellcodeexec/tree/kost/bin

Also, maybe you want to take a look at scexec which is shellcodeexec on steroids:
https://github.com/kost/scexec

it supports base64/uudecode shellcode, etc..