make-hash-tools.pl: Perl 5.14 compatibility

  https://bugs.webkit.org/show_bug.cgi?id=61890

  * make-hash-tools.pl: Use if/elsif instead of switch/case.

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@89265 268f45cc-cd09-0410-ab3c-d52691b4dbfc