phar_rename_archive() bug fix for PHP7

hi all, Phar::convertTo*() methods have a design flaw such that phar files can't be successfully converted and retain the proper file suffix at the same time when the base name contains dots. An expression of this is attempting to convert something-v3.0.0.phar to say a tar.gz via convertToExecutable(Phar::TAR, Phar::GZ); My original patch respected BC when it was destined for PHP5, but now I've cleaned it up and removed the retention of BC behavior, and I intend it to be merged to PHP7 only. As such, existing tests also needed modification. I'd like some discussion, code review ... and if no objections, some karma to commit this to master. The PR is here: https://github.com/php/php-src/pull/297 Thanks, Ralph