Warn when GL_TEXTURE_MIN_FILTER is GL_NEAREST_MIPMAP_LINEAR and no mips

Non-mipmapped textures will appear black unless the `GL_TEXTURE_MIN_FILTER` texture parameter is set to `GL_LINEAR` like so:

`glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR)`

The default for this is `GL_NEAREST_MIPMAP_LINEAR`, which will attempt to use mipmaps, often resulting in a black sample read.

This is a stupidly easy thing to encounter when writing new GL code, and we should warn about it.