[Chicken-hackers] -emit-exports won't override explicit emit

[Brandon J. Van Every]

The Chicken command line option -emit-exports FILENAME will not override 
explicit emit statements in the code.  I don't know whether that's 
desired behavior or not.

The problem is that both posixunix.scm and posixwin.scm now emit 
posix.exports.  So they collide.  In theory, both posix.exports declare 
the same functions.  In practice, I expect people to make errors about 
ensuring all Windows functions are available.  So we need to ensure 
consistency somehow.

In CMake, I've made posixwin.scm in charge of the posix.exports 
dependency.  That way, if exports go out of sync, we're more likely to 
notice.  It has a small negative side effect: posixwin.c gets recompiled 
every time posixunix.c does.  That's because posixunix.c emits 
posix.exports, the posixwin.c rule notices, and then fires again.

A command line option to suppress exports, or to send them to a 
different filename than what the emit statements say, would clear up the 
file collision.


Cheers,
Brandon Van Every