Fix shaders for OpenGL core profiles

Add also a --coreprofile command-line parameter to the gallery and
systemdialogs examples to allow testing Quick Controls with an OpenGL 3.2+
core profile.

This depends on the new features introduced to qtdeclarative in
I75a47182 and I41b513e9.

Change-Id: I408263a108a71df221943915849a4c3e18e0d3e4
Reviewed-by: Gunnar Sletta <gunnar.sletta@jollamobile.com>