[GTK] Tools/gtk/install-dependencies added ragel dependency
https://bugs.webkit.org/show_bug.cgi?id=115163

Patch by Xavier Castano <xcastanho@igalia.com> on 2013-04-25
Reviewed by Xan Lopez.

The install-dependencies script was missing a dependency on ragel
which is expected when building HarfBuzz.

* gtk/install-dependencies: Added a dependency on ragel for both
apt and yum.

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@149109 268f45cc-cd09-0410-ab3c-d52691b4dbfc