[Ohrrpgce] SVN: teeemcee/13447 Fix a win64 build error and some warnings (based on patch from Matthew)

[subversion at HamsterRepublic.com]

teeemcee
2023-12-29 14:01:06 -0800 (Fri, 29 Dec 2023)
126
Fix a win64 build error and some warnings (based on patch from Matthew)

But win64 builds don't actually work, nor can I test.
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U   wip/os_windows.bas