fixed bug w/ vstudio contrib in which incorrect relative path caused …

[Tythos]

…masmx64 script call to fail when building zlibvc project. Tested w/ VS2022, but should fix identical issue with standing ("vc14") solution. Can create a new VS2022 ("vc17") solution if desired, but the fix seemed modest enough to back-propagate.

[rhuijben]

Assembly code has been removed in latest version, as outdated and has known issues that may cause data corruption.