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.

prefix=@prefix@

exec_prefix=@exec_prefix@

libdir=@libdir@

includedir=@includedir@

Name: razor

Description: library for depsolving, installing and removing packages

Version: @VERSION@

Requires: libcurl

Libs: -L${libdir} -lexpat -lz -lrazor

Cflags: -I${includedir}/razor