[Zope-Coders] Warnings from compilation of Zope 2.6 branch

[Tim Peters]

[Chris Withers]
> While trying to debug the hanging tests problem, I also noticed
> there's a load of warning-type things from compilation of Zope from the
> 2.6 branch:
>
> BTrees/BucketTemplate.c:214: warning: `bucket_append' defined but not used
> BTrees/BucketTemplate.c:214: warning: `bucket_append' defined but not used
> BTrees/BucketTemplate.c:214: warning: `bucket_append' defined but not used

Those 3 are my fault.  I thought I fixed them "everywhere" but apparently
didn't.  bucket_append gets called if and only if a flavor of BTree supports
the multiunion function, and 3 flavors of BTree don't.  The fix is to #ifdef
out the definition of bucket_append in those flavors; it does no harm to
leave the unused function sitting around, though.

All the rest were in XML support files, and I'll defer to Fred on those.