While the current code in `FT_Get_Next_Char' correctly rejects
out-of-bounds glyph indices, it can be extremely slow for malformed
cmaps that use 32bit values. This commit tries to improve that.
* src/sfnt/ttcmap.c (tt_cmap8_char_next, tt_cmap12_next,
tt_cmap12_char_map_binary, tt_cmap13_next,
tt_cmap13_char_map_binary): Reject glyph indices larger than or
equal to the number of glyphs.