features.txt: update virgl GL4.1 status.

All the features for GL4.1 are done (64-bit attribs were part of
the fp64 enable).

Once tessellation shaders land this will be advertised

docs/features.txt

@@ -139,14 +139,14 @@ GL 4.0, GLSL 4.00 --- all DONE: i965/gen7+, nvc0, r600, radeonsi
   GL_ARB_transform_feedback3                            DONE (i965/gen7+, llvmpipe, softpipe, swr, virgl)
 
 
-GL 4.1, GLSL 4.10 --- all DONE: i965/gen7+, nvc0, r600, radeonsi
+GL 4.1, GLSL 4.10 --- all DONE: i965/gen7+, nvc0, r600, radeonsi, virgl
 
-  GL_ARB_ES2_compatibility                              DONE (freedreno, i965, nv50, llvmpipe, softpipe, swr, virgl)
+  GL_ARB_ES2_compatibility                              DONE (freedreno, i965, nv50, llvmpipe, softpipe, swr)
   GL_ARB_get_program_binary                             DONE (0 or 1 binary formats)
   GL_ARB_separate_shader_objects                        DONE (all drivers)
   GL_ARB_shader_precision                               DONE (i965/gen7+, all drivers that support GLSL 4.10)
   GL_ARB_vertex_attrib_64bit                            DONE (i965/gen7+, llvmpipe, softpipe)
-  GL_ARB_viewport_array                                 DONE (i965, nv50, llvmpipe, softpipe, virgl)
+  GL_ARB_viewport_array                                 DONE (i965, nv50, llvmpipe, softpipe)
 
 
 GL 4.2, GLSL 4.20 -- all DONE: i965/gen7+, nvc0, r600, radeonsi