IF / ELSE / ENDIF macros for M4

[Mr. Clif]

    Greetings,
    
    I heard a long time ago that CPP was derived from M4, and read that
    a few folks including myself have looked for IF / ENDIF type macros
    to use on other projects. CPP is not ideal in that it wants to take
    extra steps like tokenizing the source.
    
    Here is a post from someone else looking:
    
https://stackoverflow.com/questions/50549946/conditional-compilation-interpretation-using-m4/66978338#66978338
    
    So not finding anything like this, I wrote some that seem to work
    pretty well. Here they are:
    
    http://www.eugeneweb.com/wiki/Sites/M4Macros

I defined the names without the #'s eg. IF, ELSE, ENDIF, etc... Also M4 requires parentheses to hold the arguments where CPP does not (at least for most of these). I also added a selective invoke, to protect macros with side effects from invocation in an unselected block.

    I was wondering if they pass muster, if the devs might consider
    including them or something similar in M4's list of examples.

        Best,
        Clif