current cvs evaluates shrext before args are parsed

[Benjamin Reed]

Since on darwin shrext is dependent on whether the library is a module 
or not, shrext is set to a test that gets eval'd later.

It appears that sometime in the last month or two, changes have made it 
so that shrext is evaluated *before* the command-line arguments are 
parsed, and thus shrext is always .dylib because $module is set to no.

I've not yet tracked down where this happened, but this is likely going 
to cause issues on darwin.

The output of using "sh -x libtool" for building an arts -module is 
here, if you need to see a trace:

http://ranger.befunk.com/debug/libtool.log