[truetype] Avoid nested frames.

Triggered by

  https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=10054

* src/truetype/ttgload.c (load_truetype_glyph): Don't use variable
`opened_frame' to trace whether a frame must be closed at the end of
function: This fails because `TT_Vary_Apply_Glyph_Deltas' (which
gets called for space glyphs) uses a frame by itself.  Instead,
close the frame after loading the header, then use another frame for
the remaining part of the glyph later on.

Also avoid calling `tt_get_metrics' twice under some circumstances.
2 files changed