Fix T61172: Crash in texture paint undo/redo

Mixing texture paint undo w/ memfile undo was crashing.

The gputextures and render result are written to the FileData.imamap
but weren't read back.

source/blender/blenloader/intern/readfile.c

@@ -3938,6 +3938,12 @@ static void direct_link_image(FileData *fd, Image *ima)
 		}
 		ima->rr = NULL;
 	}
+	else {
+		for (int i = 0; i < TEXTARGET_COUNT; i++) {
+			ima->gputexture[i] = newimaadr(fd, ima->gputexture[i]);
+		}
+		ima->rr = newimaadr(fd, ima->rr);
+	}
 
 	/* undo system, try to restore render buffers */
 	link_list(fd, &(ima->renderslots));