subs, vo: do sub bitmap change detection by comparing IDs

vo_vdpau and vo_gl cache the last subtitle bitmaps uploaded to video
card in case they stay the same over multiple frames. Detecting
whether the bitmaps have changed and should be re-uploaded was
somewhat fragile. Change the VO API to provide a bitmap ID which can
be compared with what the VO has to determine whether a new upload of
the bitmaps is needed.

Conflicts:
	libvo/vo_gl.c

Note: the changes for vo_gl.c were not merged. Instead, eosd_packer is
modified to use the new way of detecting EOSD changes. This takes care
of vo_gl, vo_gl3 and vo_direct3d, which all render EOSD. They don't
need to be updated in turn.

1 files changed, 1 insertions, 1 deletions

diff --git a/sub/dec_sub.h b/sub/dec_sub.h
index f09b555685..ae39f15f31 100644
--- a/sub/dec_sub.h
+++ b/sub/dec_sub.h
@@ -12,7 +12,7 @@ typedef struct mp_eosd_res {
 
 typedef struct sub_bitmaps {
     struct ass_image *imgs;
-    int changed;
+    int bitmap_id, bitmap_pos_id;
 } mp_eosd_images_t;
 
 static inline bool is_text_sub(int type)