OpenGL extensions not queried correctly when using Core Profile with OpenGL >= 3.1

The function QGLExtensions::Extensions QGLExtensions::currentContextExtensions() uses a call to glGetString(GL_EXTENSIONS) in order to retrieve the string of supported OpenGL extensions.

When using OpenGL >= 3.1 along with the CoreProfile, the glGetString() entry point is deprecated and removed. This results in a null pointer to const char* which in turn results in Qt's OpenGL support thinking that no extensions are available at all. This then causes QGLShaderProgram to think that shaders are not supported either.

I am now going to see if I can come up with a patch to fix this. If so I'll add it as a MR on gitorious.