convert razor_package_get_details() and razor_package_iterator_next() to varargs

The functions for getting package details about a package were limited to a few
things, when in the future we will want to support much more about a package.
The iterator was also limited to name,version,arch when most of the time we
didn't need all this data.

 html

 razor-decl-list.txt

 razor-decl.txt

 razor-overrides.txt

 version.xml

 xml