sub: use Unicode linebreaking for non-ASS subs and OSD

ASS must only automatically break at ASCII spaces (\x20), but other
subtitle formats might expect more breaking oppurtinities.
Especially non-ASS subs in scripts, which typically do not use (ASCII)
spaces to seperate words, like e.g. CJK, might overflow the screen
if the conversion didn't insert additional linebreaks (ffmpeg does not).

Thus try to enable Unicode linebreaking for converted subs and the OSD
if libass is new enough. The feature may still be unavailable at runtime
if libass wasn't build with Unicode linebreaking support.

sub/osd_libass.c

@@ -133,7 +133,9 @@ static void create_ass_track(struct osd_state *osd, struct osd_object *obj,
     track->WrapStyle = 1; // end-of-line wrapping instead of smart wrapping
     track->Kerning = true;
     track->ScaledBorderAndShadow = true;
-
+#if LIBASS_VERSION >= 0x01600010
+    ass_track_set_feature(track, ASS_FEATURE_WRAP_UNICODE, 1);
+#endif
     update_playres(ass, &obj->vo_res);
 }
 

sub/sd_ass.c

@@ -442,6 +442,10 @@ static void configure_ass(struct sd *sd, struct mp_osd_res *dim,
     ass_set_font_scale(priv, set_font_scale);
     ass_set_hinting(priv, set_hinting);
     ass_set_line_spacing(priv, set_line_spacing);
+#if LIBASS_VERSION >= 0x01600010
+    if (converted)
+        ass_track_set_feature(track, ASS_FEATURE_WRAP_UNICODE, 1);
+#endif
 }
 
 static bool has_overrides(char *s)