call glewInit in vcl's OpenGLContext just once
call glewInit in vcl's OpenGLContext just once

Change-Id: I9f9b50615e588e659c7fcdd016cf9ceb8407b974

JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core