mesa: don't flag _NEW_SCISSOR for st/mesa

Not needed and we get to bypass _mesa_update_state_locked that would be
a no-op.

Reviewed-by: Nicolai Hähnle <nicolai.haehnle@amd.com>
Reviewed-by: Brian Paul <brianp@vmware.com>
Reviewed-by: Timothy Arceri <tarceri@itsqueeze.com>

src/mesa/main/enable.c

@@ -670,7 +670,8 @@ _mesa_set_enable(struct gl_context *ctx, GLenum cap, GLboolean state)
             GLbitfield newEnabled =
                state * ((1 << ctx->Const.MaxViewports) - 1);
             if (newEnabled != ctx->Scissor.EnableFlags) {
-               FLUSH_VERTICES(ctx, _NEW_SCISSOR);
+               FLUSH_VERTICES(ctx, ctx->DriverFlags.NewScissorTest ? 0 :
+                                                                _NEW_SCISSOR);
                ctx->NewDriverState |= ctx->DriverFlags.NewScissorTest;
                ctx->Scissor.EnableFlags = newEnabled;
             }
@@ -1115,7 +1116,8 @@ _mesa_set_enablei(struct gl_context *ctx, GLenum cap,
          return;
       }
       if (((ctx->Scissor.EnableFlags >> index) & 1) != state) {
-         FLUSH_VERTICES(ctx, _NEW_SCISSOR);
+         FLUSH_VERTICES(ctx,
+                        ctx->DriverFlags.NewScissorTest ? 0 : _NEW_SCISSOR);
          ctx->NewDriverState |= ctx->DriverFlags.NewScissorTest;
          if (state)
             ctx->Scissor.EnableFlags |= (1 << index);

src/mesa/main/scissor.c

@@ -48,7 +48,7 @@ set_scissor_no_notify(struct gl_context *ctx, unsigned idx,
        height == ctx->Scissor.ScissorArray[idx].Height)
       return;
 
-   FLUSH_VERTICES(ctx, _NEW_SCISSOR);
+   FLUSH_VERTICES(ctx, ctx->DriverFlags.NewScissorRect ? 0 : _NEW_SCISSOR);
    ctx->NewDriverState |= ctx->DriverFlags.NewScissorRect;
 
    ctx->Scissor.ScissorArray[idx].X = x;