[GTK] Bump dependency on GTK+ 3.x to match reality

[GTK] Bump dependency on GTK+ 3.x to match reality
https://bugs.webkit.org/show_bug.cgi?id=84060

Rubber-stamped by Martin Robinson.

.:

* configure.ac: Bump GTK+ 3 requirement to 3.4.0. In practice we
already depend on this version because of our dependency on a recent
glib, which causes linking issues with older GTK+; also bump glib to
its earliest version.

Tools:

* gtk/jhbuild.modules: Bump GTK+ to 3.4.0, plus glib and gdk-pixbuf
to their GNOME 3.4 versions.
* gtk/patches/gtk+-3.0.12-gtkprinter.patch: Removed. This patch
is applied upstream.

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@114297 268f45cc-cd09-0410-ab3c-d52691b4dbfc