display: change default OpenGL version for Qt gui

display: change default OpenGL version for Qt gui

There are 2 issues:
With some Radeon GPU,
the Qt5 library makes runtime errors infinitely with glCreateShader
like below in Qt5 internal implementations:
'Implicit version number 110 not supported by GL3 forward compatible context'
The issue that VIGS uses OpenGL version 2,
    : starts with the force legacy option(gl_version=2).
    : User's GPU driver does not support OpenGL version 3.2.

In order to avoid these problems, use the OpenGL 3.2 Core Profile
instead of the OpenGL 3.1 to create shared context.
And after creating the shared context, reset to OpenGL versio 2.1.

Change-Id: I2d67580827b1eda53478adccf774d9ab1342b42a
Signed-off-by: Jinhyung Jo <jinhyung.jo@samsung.com>