nv50: mark scissors/viewports dirty on context switch

Commit 246ca4b001 ("nv50: implement multiple viewports/scissors, enable
ARB_viewport_array") added dirty tracking to scissors/viewports. However
it neglected to mark them all as dirty on a context switch. This fixes
an apparent regression in webgl in chrome, but probably in any
application that switches contexts.

Signed-off-by: Ilia Mirkin <imirkin@alum.mit.edu>

src/gallium/drivers/nouveau/nv50/nv50_state_validate.c

@@ -366,6 +366,8 @@ nv50_switch_pipe_context(struct nv50_context *ctx_to)
       ctx_to->state = ctx_from->state;
 
    ctx_to->dirty = ~0;
+   ctx_to->viewports_dirty = ~0;
+   ctx_to->scissors_dirty = ~0;
 
    if (!ctx_to->vertex)
       ctx_to->dirty &= ~(NV50_NEW_VERTEX | NV50_NEW_ARRAYS);