gallium: add PIPE_CAP_STREAM_OUTPUT_INTERLEAVE_BUFFERS

This allows the driver to signal that it can't handle random
interleaving of attributes across buffers. This is required for
ARB_transform_feedback3, and it's initialized to whatever the previous
value of PIPE_CAP_STREAM_OUTPUT_PAUSE_RESUME was except for nv50 where
it is disabled. Note that the proprietary drivers never expose
ARB_transform_feedback3 on any GT21x's (where nouveau previously did),
and after some effort I was unable to get it to work.

Signed-off-by: Ilia Mirkin <imirkin@alum.mit.edu>
Reviewed-by: Nicolai Hähnle <nicolai.haehnle@amd.com>
Reviewed-by: Marek Olšák <marek.olsak@amd.com>
diff --git a/docs/features.txt b/docs/features.txt
index a677bfb..2c6691f 100644
--- a/docs/features.txt
+++ b/docs/features.txt
@@ -133,7 +133,7 @@
   GL_ARB_texture_gather                                 DONE (i965/gen6+, nv50, llvmpipe, softpipe, swr)
   GL_ARB_texture_query_lod                              DONE (i965, nv50, softpipe)
   GL_ARB_transform_feedback2                            DONE (i965/gen7+, nv50, llvmpipe, softpipe, swr)
-  GL_ARB_transform_feedback3                            DONE (i965/gen7+, nv50, llvmpipe, softpipe, swr)
+  GL_ARB_transform_feedback3                            DONE (i965/gen7+, llvmpipe, softpipe, swr)
 
 
 GL 4.1, GLSL 4.10 --- all DONE: i965/gen8+, nvc0, r600, radeonsi