Potential solution for DELETE_OLD on Windows

[ThenTech]

See comment in #111.

Changes:

• Let git force Unix line endings
• Don't redefine _CRT_SECURE_NO_WARNINGS if already defined (by cl.exe commands)
• Add MOVEFILE_WRITE_THROUGH in nob_rename so the function doesn't return until the file is actually written
• When rebuilding nob, add a --nob-delete-old argument to tell the new nob to delete the old one, and run the new one async, so the old one can exit and release its own process handle