When updating text from file periodically, newer glyphs that weren't
already cached would not end up being rendered. This fixes the issue by
calling cache_glyphs after the file has been updated.
How to reproduce the original issue:
Set a text-freetype2 source to load an english-only text file. Then
overwrite the text in the file with non-english characters. The
non-english characters will then fail to render.
Reported at https://obsproject.com/mantis/view.php?id=336Closesjp9000/obs-studio#481
c4f5769df4