Introduce QT_OPENGL_ES_2_ANGLE_STATIC define for static builds
and modify export accordingly. Provided static instances
of gl::Current and egl::Current for Qt's single threaded
use.
Task-number: QTBUG-28196
Change-Id: Ia75699d6da103fb8dd9d5fe97c1ee51e48a74406
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@digia.com>
Reviewed-by: Kai Koehne <kai.koehne@digia.com>