softpipe: enable ARB_texture_view

Some bits were already there for texture views but some were missing.
In particular for cube map views things needed to change a bit.
For simplicity I ended up removing the separate face addr bit (just use
the z bit) - cube arrays didn't use it already, so just follow the same
logic there. (In theory using separate bits could allow for better hash
function but I don't think anyone ever did some measurements of that so
probably not worth the trouble, if we'd reintroduce it we'd certainly
wanted to use the same logic for cube arrays and cube maps.)
Also extend the seamless cube sampling to cube arrays - as there were no
piglit failures before this is apparently untested, but things now generally
work quite the same for cube textures and cube array textures so there
hopefully shouldn't be any trouble...

49 new piglits, 47 pass, 2 fail (both due to fake multisampling).

v2: incorporate Brian's feedback, add sampler view validation,
function rename, formatting fixes.

Reviewed-by: Brian Paul <brianp@vmware.com>

docs/GL3.txt

@@ -169,7 +169,7 @@ GL 4.3, GLSL 4.30:
   GL_ARB_texture_buffer_range                          DONE (nv50, nvc0, i965, r600, radeonsi, llvmpipe)
   GL_ARB_texture_query_levels                          DONE (all drivers that support GLSL 1.30)
   GL_ARB_texture_storage_multisample                   DONE (all drivers that support GL_ARB_texture_multisample)
-  GL_ARB_texture_view                                  DONE (i965, nv50, nvc0, llvmpipe)
+  GL_ARB_texture_view                                  DONE (i965, nv50, nvc0, llvmpipe, softpipe)
   GL_ARB_vertex_attrib_binding                         DONE (all drivers)
 
 

docs/relnotes/10.6.0.html

@@ -56,7 +56,7 @@ Note: some of the new features are only available with certain drivers.
 <li>GL_ARB_pipeline_statistics_query on i965, nv50, nvc0, r600, radeonsi, softpipe</li>
 <li>GL_ARB_program_interface_query (all drivers)</li>
 <li>GL_ARB_texture_stencil8 on nv50, nvc0, r600, radeonsi, softpipe</li>
-<li>GL_ARB_texture_view on llvmpipe</li>
+<li>GL_ARB_texture_view on llvmpipe, softpipe</li>
 <li>GL_ARB_uniform_buffer_object on freedreno</li>
 <li>GL_ARB_vertex_attrib_64bit on nvc0, softpipe</li>
 <li>GL_ARB_viewport_array, GL_AMD_vertex_shader_viewport_index on i965/gen6</li>