gallium: add a is_dri_blit_image bool to pipe_blit_info

This indicates driver that a given blit is coming from the DRI
frontend.
This information can then be used to pick an appropriate blitting
method.

Reviewed-by: Marek Olšák <marek.olsak@amd.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/12763>

src/gallium/frontends/dri/dri2.c

@@ -1704,6 +1704,7 @@ dri2_blit_image(__DRIcontext *context, __DRIimage *dst, __DRIimage *src,
    blit.src.format = src->texture->format;
    blit.mask = PIPE_MASK_RGBA;
    blit.filter = PIPE_TEX_FILTER_NEAREST;
+   blit.is_dri_blit_image = true;
 
    pipe->blit(pipe, &blit);
 

src/gallium/include/pipe/p_state.h

@@ -900,6 +900,7 @@ struct pipe_blit_info
    bool render_condition_enable; /**< whether the blit should honor the
                                  current render condition */
    bool alpha_blend; /* dst.rgb = src.rgb * src.a + dst.rgb * (1 - src.a) */
+   bool is_dri_blit_image;
 };
 
 /**