Remove two unused variables from iter_packages()

The code using the variables was refactored in 694d614b. As a result
they were still set in iter_packages() but never subsequently used.

Signed-off-by: Adam D. Barratt <adam@adam-barratt.org.uk>

britney.py

@@ -2135,8 +2135,6 @@ class Britney(object):
 
                 nuninst[arch] = set([x for x in nuninst_comp[arch] if x in binaries[arch][0]])
                 nuninst[arch + "+all"] = set([x for x in nuninst_comp[arch + "+all"] if x in binaries[arch][0]])
-                broken = nuninst[arch + "+all"]
-                to_check = []
 
                 check_packages(arch, affected, skip_archall, nuninst, pkg)