mesa: Unbind deleted vbo using _mesa_bind_vertex_buffer.

When a vertex buffer object gets deleted, it is unbound
at the VAO. To do this use _mesa_bind_vertex_buffer instead
of plain unreferencing the buffer object. This keeps the VAOs
internal state consistent. In this case it showed up with
gl_vertex_array_object::VertexAttribBufferMask getting out of
sync.

Signed-off-by: Mathias Fröhlich <Mathias.Froehlich@web.de>
Reviewed-by: Eric Anholt <eric@anholt.net>

src/mesa/main/bufferobj.c

@@ -44,6 +44,7 @@
 #include "glformats.h"
 #include "texstore.h"
 #include "transformfeedback.h"
+#include "varray.h"
 
 
 /* Debug flags */
@@ -1199,11 +1200,13 @@ _mesa_multi_bind_lookup_bufferobj(struct gl_context *ctx,
  */
 static void
 unbind(struct gl_context *ctx,
-       struct gl_buffer_object **ptr,
+       struct gl_vertex_array_object *vao, unsigned index,
        struct gl_buffer_object *obj)
 {
-   if (*ptr == obj) {
-      _mesa_reference_buffer_object(ctx, ptr, ctx->Shared->NullBufferObj);
+   if (vao->VertexBinding[index].BufferObj == obj) {
+      _mesa_bind_vertex_buffer(ctx, vao, index, ctx->Shared->NullBufferObj,
+                               vao->VertexBinding[index].Offset,
+                               vao->VertexBinding[index].Stride);
    }
 }
 
@@ -1302,7 +1305,7 @@ _mesa_DeleteBuffers(GLsizei n, const GLuint *ids)
 
          /* unbind any vertex pointers bound to this buffer */
          for (j = 0; j < ARRAY_SIZE(vao->VertexBinding); j++) {
-            unbind(ctx, &vao->VertexBinding[j].BufferObj, bufObj);
+            unbind(ctx, vao, j, bufObj);
          }
 
          if (ctx->Array.ArrayBufferObj == bufObj) {