Pin qtbase version so we can integrate glyph format changes

Will be unpined along with an update that matches the changes in
https://codereview.qt-project.org/#change,77791

Change-Id: I5b9572d21e2cca8dc0078eb0079f6d42af6dd6d4
Reviewed-by: Simon Hausmann <simon.hausmann@digia.com>

sync.profile

@@ -18,6 +18,6 @@
 #   - an empty string to use the same branch under test (dependencies will become "refs/heads/master" if we are in the master branch)
 #
 %dependencies = (
-        "qtbase" => "",
+        "qtbase" => "4273c14e57d26cf2dde90ed9db1f463a25b327bd",
         "qtxmlpatterns" => "",
 );