swr: add PIPE_CAP_FRAMEBUFFER_NO_ATTACHMENT to get_param

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

src/gallium/drivers/swr/swr_screen.cpp

@@ -342,6 +342,7 @@ swr_get_param(struct pipe_screen *screen, enum pipe_cap param)
    case PIPE_CAP_PCI_BUS:
    case PIPE_CAP_PCI_DEVICE:
    case PIPE_CAP_PCI_FUNCTION:
+   case PIPE_CAP_FRAMEBUFFER_NO_ATTACHMENT:
       return 0;
    }