> Using a flag instead of a new texture target allows to avoid hundreds of
> changes to existing code, and allows drivers for modern hardware to
> just ignore this flag.
I grepped a bit through the code, and a new texture target seems
easier than expected: apparently there are only about 36 checks
This is a mix of my first and second attempts, and tries to include the
best received parts from each.
In general, it tries to be both unobtrusive, and have clean semantics.
>From the first attempt, it restores the usage of a single st->driver flag
instead of 4 bind flags, which is now called
PIPE
