added more test coverage for distutils.filelist to prevent regressions when fnmatch or re are changed

fixed how fnmatch.translate is used (since it has changed in r74475 for #6665). Now the code is not harcoding the usage of $ anymore

Issue #6545: Removed assert statements in distutils.Extension, so the behavior is similar when used with -O

Fixed #6377: distutils compiler switch ignored (and added a deprecation warning if compiler is not used as supposed = a string option)

Fixes #6258.