ext_texture_format_bgra8888: test glRenderbufferStorage
While it might seem unintuitive, the spec here actually adds GL_BGRA_EXT as a color-renderable format, which means it's usable for glRenderBufferstorage() as well. So we should test that.
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While it might seem unintuitive, the spec here actually adds GL_BGRA_EXT as a color-renderable format, which means it's usable for glRenderBufferstorage() as well. So we should test that.