ddebug: write out final driver log messages with GALLIUM_DDEBUG=always

If the last operation happens to be a non-draw, such as a
transfer_map that triggers a decompress blit, there may be
interesting messages left in the driver log.

Reviewed-by: Marek Olšák <marek.olsak@amd.com>

src/gallium/drivers/ddebug/dd_draw.c

@@ -39,7 +39,7 @@
 #include <inttypes.h>
 
 
-static FILE *
+FILE *
 dd_get_file_stream(struct dd_screen *dscreen, unsigned apitrace_call_number)
 {
    struct pipe_screen *screen = dscreen->screen;