- check namespaces of dependencies in _rpmtsCheck, don't compare strings blindly

- check namespaces of dependencies in _rpmtsCheck, don't compare strings blindly

This patch fixes a bug with ntpd package we encoutered:
- ntpdate has "Conflicts: ntp < 4.2.0-3"
- ntpd has "Provides: ntp = 4.2.4" and "Provides: user(ntp)"
now, if ntpdate is installed then attempt to install ntpd causes
_rpmtsCheck to compare "C: ntp" to both "P: ntp" AND THEN "P: user(ntp)"
due to lack of dependency namespace check. Side effect of this is
infinite loop in _rpmtsCheck due to inner workings of rpm dependency
iterators.