(AIX) Exclude arch from uninstall on old RPMs

Prior to this commit, the RPM provider assumed that `rpm` would
know what to do with the architecture (e.g. i386, x86_64, ppc)
when uninstalling a packages (e.g. `rpm -e mypkg.i386`).
Unfortunately, this only works for relatively modern versions of
`rpm` (4.2.1+).  This commit checks the version of `rpm` and will
add or exclude the architecture from the arguments sent to `rpm`.

Sprintly: fix item:251
(AIX) Remove RPM test from yum spec

Prior to this commit, the yum package provider spec was testing
functionality that did not exist in the yum package provider, but
rather in its parent, the rpm package provider. This commit removes
that test because now we have a proper rpm provider spec.