Implement INCLUDE_ONCE directive

[sukus21]

Fixes #1478.

This behaves like regular include the first time a file is included, except the name of the file is added to a list. The next time using INCLUDE_ONCE on that file, the file will not be included. INCLUDE_ONCE does not take symlinks into account. The string that is registered, is the one entered into the directive.

This is effectively an include guard, not unlike C/C++ #PRAGMA ONCE.

[Rangi42]

Thank you for this contribution! However, it's somewhat premature; a feature-request issue is already open, and the blocker is "getting community confirmation that this is worth adding", not "being able to implement it technically".

[Rangi42]

I pushed to this myself to update the man page wording/formatting a bit. Edit: And to fix the failing test.

[Rangi42]

Thank you for your work on this! Looks good to me, if we choose to add this feature. Pending @ISSOtm's approval as well.

[ISSOtm]

What about a.asm includes d/b.inc then b.inc, with -I d?

[ISSOtm]

Furthermore, what about -P, symlinks, and other platform-specific goodness? Path manipulation introduces more platform-specific behaviour, and I don't like going further down that avenue.

[Rangi42]

-P calls the same fstk_RunInclude function that INCLUDE does, as it always has. -I is handled via the trivially cross-platform fstk_FindFile "path manipulation" function, as it always was. We both know that nobody is going to symlink bar.inc to foo.inc and rely on INCLUDE_ONCE treating them both the same, but I went ahead and handled that over-the-edge case anyway. :P

Resolved