Cube textures must be cube complete to generate mipmaps, but when the base level is undefined the glGenerateMipmap command must be silently ignored. This was previously leading to a null dereference. Bug chromium:924022 Bug https://gitlab.khronos.org/opengl/API/issues/72 Change-Id: I5d6e8533118e554efa12045fc376126c7b00f263 Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/27491 Presubmit-Ready: Nicolas Capens <nicolascapens@google.com> Tested-by: Nicolas Capens <nicolascapens@google.com> Kokoro-Presubmit: kokoro <noreply+kokoro@google.com> Reviewed-by: Alexis Hétu <sugoi@google.com>
