vcl: Release the OpenGL context for offscreen rendering after each operation
vcl: Release the OpenGL context for offscreen rendering after each operation

Change-Id: If253a4c0a1f64b1cc54e0079d4455abf39620ac0

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