Fixed static linking against QtGui and QtOpenGL

When linking QtGui and QtOpenGL libraries on linux a multiple defined
symbols linker error causes failure. This change renames the offending
class in the QtOpenGL library. For more information see:

http://qt-project.org/forums/viewthread/27458

Change-Id: I05488bf2c5c612476432c11095b24bc2b29c78f2
Reviewed-by: Samuel Rødal <samuel.rodal@digia.com>