[GTK][CMake] Add a 'distcheck' target

[GTK][CMake] Add a 'distcheck' target
https://bugs.webkit.org/show_bug.cgi?id=130675

.:
Reviewed by Gustavo Noronha Silva.

* Source/PlatformGTK.cmake: Add distcheck target.

Tools:
Patch by Carlos Garcia Campos  <cgarcia@igalia.com> and Martin Robinson <mrobinson@igalia.com> on 2014-07-10
Reviewed by Gustavo Noronha Silva.

Add --check option to make-dist script that builds and installs the tarball.

* gtk/make-dist.py:
(Distcheck.__init__):
(Distcheck.extract_tarball): Extratc the tarball.
(Distcheck.configure): Run cmake.
(Distcheck.configure.create_dir): Helper function to create a directory.
(Distcheck.build): Run make.
(Distcheck.install): Run make install.
(Distcheck.clean): Clean up the extracted tarball.
(Distcheck.check): Run all previous methods in order.
* gtk/manifest.txt: Add missing file.

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@170965 268f45cc-cd09-0410-ab3c-d52691b4dbfc