[GTK] Update build dependencies
https://bugs.webkit.org/show_bug.cgi?id=115111

Patch by Simon Pena <simon.pena@samsung.com> on 2013-04-24
Reviewed by Martin Robinson.

The install-dependencies script was missing a dependency on EGL,
which is expected when building Cairo.

* gtk/install-dependencies: Added a dependency on libegl1-mesa
for both apt and yum.

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@149048 268f45cc-cd09-0410-ab3c-d52691b4dbfc