openGL: load lobGL calls explicitly if openGLES support is enabled

openGL: load lobGL calls explicitly if openGLES support is enabled

If we enable openGLES support then QEMU links with libGL and`libGLES, which
has the same symbols. This results in unpredictable behaviour.

Open libGL explicitly if openGLES is enabled and use function handlers to call
openGL functions.

Signed-off-by: Igor Mitsyanko <i.mitsyanko@samsung.com>