Fixes example 08 when using OpenGL (#2233)
Fixes example 08 when using OpenGL (#2233)

This example was broken on Windows and Linux when using OpenGL.
The code path when using immutable compressed textures was wrong.
bkaradzic/bgfx,bkaradzic/bgfx,jdryg/bgfx,bkaradzic/bgfx,bkaradzic/bgfx,jdryg/bgfx,jdryg/bgfx,mendsley/bgfx,emoon/bgfx,emoon/bgfx,LWJGL-CI/bgfx,jdryg/bgfx,mendsley/bgfx,emoon/bgfx,LWJGL-CI/bgfx,mendsley/bgfx,LWJGL-CI/bgfx,LWJGL-CI/bgfx