Nvidia's driver defaults invalid enumerations to GL_CLAMP. Vulkan
doesn't expose GL_CLAMP through its API, but we can hack it on Nvidia's
driver using the internal driver defaults.
The OpenGL spec defines GL_CLAMP's formula similarly to CLAMP_TO_EDGE
and CLAMP_TO_BORDER depending on the filter mode used. It doesn't
exactly behave like this, but it's the closest we can get with what
Vulkan offers without emulating it by injecting shader code.
