Menu text drawn with characters the bitmap sheets lack (Chinese, Japanese,
Korean) is rasterized into a reserve of the shared atlas at run time, and the
font caches the atlas rect it got. The loading screen hands over to the game
about two seconds after the title shows by building a new renderer, whose
atlas texture is made from HudAtlas.pixels alone: those never hold a
run-time glyph, while the cache still answers with the old rects, so every
such character already drawn went blank. Latin text, straight from the
sheets, stayed. build_renderer and loading_renderer now forget the cache
before the new texture exists, so the characters that are drawn again are
placed into it, as ui_theme clears its own cache when the atlas changes.
Fixes#1824, fixes#2040.
kohad1ck
5ec21ff5f1