glsl: make component_slots() returns 2 for samplers/images

glsl: make component_slots() returns 2 for samplers/images

Bindless samplers/images are 64-bit unsigned integers, which
means they consume two components as specified by
ARB_bindless_texture.

It looks like we are not wasting uniform storage by changing
this because default-block uniforms are not packed. So, if
we use N uint uniforms, they occupy N * 16 bytes in the
constant buffer. This is something that could be improved.

Though, count_uniform_size needs to be adjusted to not count
a sampler (or image) twice.

As a side effect, this will probably break the cache if you
have one because it will consider sampler/image types as
two components.

v3: - update the comments

Signed-off-by: Samuel Pitoiset <samuel.pitoiset@gmail.com>
Reviewed-by: Nicolai Hähnle <nicolai.haehnle@amd.com>
Reviewed-by: Timothy Arceri <tarceri@itsqueeze.com>