import-checker: fix names of dynamically loaded modules The import checker found standard library modules such as lib-dynload/zlibmodule.so but saw that as a 'zlibmodule' module, not as the 'zlib' module. Debian ships Python with most modules built-in and this incorrect handling of dynamic modules did thus not cause problems on that platform. Fedora ships Python with as many modules as possible loaded dynamically. That made the import checker tests fail with incorrect classification of the following modules: array fcntl grp itertools time zlib. This change makes test-module-imports.t pass on Fedora.