svr4pkg supports the -G switch for pkgadd

By standard, pkgadd adds an package in the global zones and all non-global zones. But with an configuration management, you maybe dont want to have this behavior. pkgadd supports the -G switch, which triggers an installation only in the current zone. This pullrequest enables this switch for the package svr4pkg, but doesn't set is as default (it would break Solaris 9 support)

This pull request is nearly identical to the request ansible/5873 (with fixed default behaviour)