So removed the inline statements on the functions that were missing. All errors are gone except,
sdl.c: In function 'Pause':
sdl.c:892:9: warning: variable 'Pt' set but not used [-Wunused-but-set-variable]
892 | POINT Pt;
| ^~
Which causes errors related to Pt.x and Pt.y if commented out.
I did have those other warnings previously even though the build succeeded so I figure good to fix the warnings anyways and removing some inlines shouldn't matter on most all hardware.
Here's the current binary. Martin, if no one comments with a better way fix, should use this binary as it corresponds to the source changes I'll push tomorrow after renewing my password token.