st/mesa: pass GL_MAP_INVALIDATE_RANGE_BIT to gallium drivers

when mapping renderbuffers or texture images.

NOTE: This is a candidate for the 8.0 branch.

src/mesa/state_tracker/st_cb_fbo.c

@@ -688,6 +688,8 @@ st_MapRenderbuffer(struct gl_context *ctx,
       usage |= PIPE_TRANSFER_READ;
    if (mode & GL_MAP_WRITE_BIT)
       usage |= PIPE_TRANSFER_WRITE;
+   if (mode & GL_MAP_INVALIDATE_RANGE_BIT)
+      usage |= PIPE_TRANSFER_DISCARD_RANGE;
 
    /* Note: y=0=bottom of buffer while y2=0=top of buffer.
     * 'invert' will be true for window-system buffers and false for

src/mesa/state_tracker/st_cb_texture.c

@@ -189,6 +189,8 @@ st_MapTextureImage(struct gl_context *ctx,
       pipeMode |= PIPE_TRANSFER_READ;
    if (mode & GL_MAP_WRITE_BIT)
       pipeMode |= PIPE_TRANSFER_WRITE;
+   if (mode & GL_MAP_INVALIDATE_RANGE_BIT)
+      pipeMode |= PIPE_TRANSFER_DISCARD_RANGE;
 
    map = st_texture_image_map(st, stImage, slice, pipeMode, x, y, w, h);
    if (map) {